Fulton's Condition Research Articles

Length-weight relationships and condition factors ofmullets Liza macrolepisand Moolgarda engeli(Pisces: Mugilidae) harvested from Lambada Lhok waters in Aceh Besar, Indonesia.

Background: The mullets fish Liza macrolepis and Moolgarda engeli are predominant in the Lambada Lhok waters in Aceh province. At present, no scientific report on this species in Aceh waters is available. Therefore, the objective of the present study is to examine the growth pattern and condition factor of the species of mullets L. macrolepis and M. engeli harvested from the aforementioned coastal waters. Methods: The sampling was done in three locations in the Lambada Lhok waters from July to November 2018. The fish were captured using gillnets from 6:00 AM to 3:00 PM four times a month for five months. A total of 242 L. macrolepis and 109 M. engeli were used for the analysis. The growth pattern was analyzed using linear allometric model; then, two condition factors, Fulton's and relative weight, were calculated. Results: The study revealed a b value of 2.49 for the male L. macrolepis and 1.81 for the female. The b value was 3.22 for the male M. engeli and 3.41 for the female. The b value of the fish was higher during the dry season. The Fulton's condition factor of the male L. macrolepis was 1.19, and that of the female was 1.19. The relative condition factor of this species was 100.11 and 100.01 for males and females, respectively. The Fulton condition factor of male M. engeli was 1.05 and that of the female was 1.06. The relative weight condition factors were 101.08 and 100.61 for the male and female, respectively. Conclusions:The growth pattern of M. engelitends to be isometric, whereas that of L. macrolepishas a negative allometric growth pattern. The condition factors indicate that the Lambada Lhok waters are still in good condition and support the growth of the mullets, but M. engeliis more adaptable than L. macrolepis.

Human Health Implication of Major and Trace Elements Present in Commercial Crustaceans of a Traditional Seafood Marketing Region, Egypt.

The present study focused on the distribution of some major and trace elements (S (as SO42-), Na, K, B, Ca, Mg, F, Li, Al, Fe, Zn, Cu, Mn, Ni, Co, Cd, and Pb) in both flesh (Fl) and total cephalon/exoskeleton (C/E) tissues of selected crustacean species obtained from an Egyptian traditional seafood marketing region. The sequence of studied elements in (Fl) and (C/E) tissues in descending orders was S (as SO42-) > Na > K > B > Mg > Ca > Li > F > Al > Zn > Fe > Cu > Pb > Ni > Mn > Co > Cd, and S (as SO42-) > Na > B > K > Mg > Ca > F > Li > Al > Fe > Cu > Zn > Mn > Pb > Ni > Co > Cd, respectively. Both length-weight relationship and Fulton's condition factor showed the physical and biological statuses of the crustaceans. Ion quotient calculations of the studied tissues pointed to their importance in decreasing hypertension, preeclampsia, and heart disease. Human health risk due to the consumption of the crustacean species was determined using some guideline limits, metal pollution index (MPI), estimated daily intake (EDI), health comparison values (CVs), dietary intake (DRI-ULs), target hazard quotient (THQ), total target hazard quotient (TTHQ), and provisional tolerable weekly intake (%PTWI). MPI values of cephalon/exoskeleton tissues were greater than those of the flesh with ranges between 11.4-24.0 and 4.6-14.3, respectively. Interestingly, the calculations of TTHQ of toddler and adult were lesser than one and not expected to pose any risk concern to human from crustaceans' consumption.

Genetic relationship between koi herpesvirus disease resistance and production traits inferred from sibling performance in Amur mirror carp

Koi herpesvirus disease (KHVD) is currently the most serious threat to global carp farming. Prevention is a sensible strategy for tackling this disease and improved genetic resistance of carp strains is a desirable breeding goal. To study the potential for multitrait selection, the objective of the current study was to estimate the genetic correlations between KHVD resistance and production traits in Amur mirror carp. A total of 1500 fingerlings from four factorial crosses of five dams and ten sires were challenged with Koi herpesvirus (KHV). Juvenile growth-related traits were collected on the same individuals before the challenge test. Production traits were measured on siblings of the challenged population at different life stages (yearling to market size). The estimated heritability for resistance to KHVD was 0.43 ± 0.08 on the observed scale and 0.72 ± 0.13 on the underlying liability scale. Most genetic correlations between KHVD resistance and important production traits were insignificant, showing that selection for improved production traits would not increase susceptibility to KHV and vice versa. However, resistance to KHVD was negatively correlated with Fulton's condition factor (FC) after the second overwintering and relative head length (RHL), relative body height (RBH) and relative body width (RBW) from the second growing season to the market size, with a more prolonged body shape of Amur mirror carp (genes from Amur wild scaly carp, Cyprinus rubrofuscus) being associated with higher KHVD resistance. Intermediate favorable genetic correlations between KHVD resistance and log-log residuals of headless carcass yield (0.37 ± 0.14) and fillet yield (0.44 ± 0.13) at market size suggested that selection for improved yields of edible body parts might indirectly lead to a slight improvement in KHVD resistance and vice versa.

Study of Morphometric Characteristics of Freshwater Putul, Botia lohachata in Kompo River of Bagmara, Rajshahi, Bangladesh

This study described about the morphometric characteristics of Botia lohachata, collected from the Kompo River at Rajshahi , were studied for a period of four months from July to October 2014. Length frequency distributions, length-length relationships, length-weight relationship, sex ratio, Fulton's condition factor and fecundity of B. lohachata were studied in the present study. This is the maiden research conducted on B. lohachata in Bangladesh. The highest mean total lengths were 61.16±4.77 mm (combined sex), 63.80±4.79mm (female) and 58.17 ±3.30mm (male). Maximum 43.34% female fishes were belonging to the length category of 61-65 mm where as 61.41% male were belonging to 56-60 mm. Similar findings are also presented for standard length, fork length, body depth, dorsal length, pectoral length, pelvic length and anal length. Linear relationships were also studied among mentioned lengths. Strong positive correlations were observed in all cases. The highest mean body weight was weight 2.67±0.71g (October) in combined sex, this value was 3.10±0.59 in female (September) and 2.25±0.38g in male (September). Strong positive correlations were also observed between total length and body weight. Observed value of sex indicated that 54% specimens were female and remaining 46% were male. The value of chi square (x2) was 2.4 at 1 degree of freedom (p<0.005) strongly indicated that the observed sex ratio not differs significantly from the expected ratio (1:1).The Fulton’s condition factors In case of combined sexes, the highest condition factor 1.156±0.126 was recorded in month of October, female highest condition factor 1.190±0.136 and male highest condition factor 1.135±0.103.
 Journal of Science Foundation 2019;17(1):15-33

Impact of reservoir properties on elemental accumulation and histopathology of European perch (Perca fluviatilis).

This study was conducted on individuals of European perch from six reservoirs in Serbia with different properties, used for different purposes, and situated at different altitudes. Samples of muscle, gills, and liver, as well as water samples, were used for analysis of elemental accumulation. Histopathological (HP) analysis of gills and liver, and Fulton's condition factor (CF) were used as biomarkers. Analysis of Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Se, Si, Sr, and Zn was conducted by inductively-coupled plasma optical emission spectrometry (ICP-OES), and accordingly, metal pollution index and bioaccumulation factor (BAF) were calculated. Elemental accumulation varied considerably both among tissues and reservoirs. Reservoirs located on large low-altitude rivers were the most heavily polluted with metals (Međuvršje, on the Zapadna Morava River, and Lake Sava, on the Sava River). Of three tissues analyzed, the gills were most affected by pollution. The levels of Hg in muscle decreased with an increase in reservoir altitude. Specimens sampled from the highest altitude reservoir were the least affected by HP alterations; however, HP differences between the reservoirs were not statistically significant, and the severity of HP changes was generally low. No significant correlations between the elemental accumulation or HP indices with CF were observed.

Associations Between Chronic Exposure to Polycyclic Aromatic Hydrocarbons and Health Indices in Gulf of Mexico Tilefish (Lopholatilus chamaeleonticeps) Post Deepwater Horizon.

A time series of polycyclic aromatic hydrocarbon (PAH) data was collected for Gulf of Mexico demersal fishes in the years following the Deepwater Horizon oil spill (2012–2017). Tilefish (Lopholatilus chamaeleonticeps) were sampled via demersal longline at repeat stations in the northern Gulf of Mexico in 2012 to 2015 and 2017. Bile samples (n = 256) were analyzed via high‐performance liquid chromatography with fluorescence detection for PAH metabolites as a biomarker of exposure to PAHs. Liver tissues (n = 230) were analyzed for accumulation of PAHs and alkylated homologs via quick, easy, cheap, effective, rugged, and safe (QuEChERS) extractions and gas chromatography–tandem mass spectrometry quantification. Over the 6‐yr time series, exposure to petrogenic PAHs increased by an average of 178%, correlating with an average 22% decline in Fulton's condition factor. The decline in Fulton's condition factor was positively correlated with a 53% decline in percentage of liver lipid. There was no accumulation of PAHs in liver tissue over time. Together, these results suggest that increasing and chronic PAH exposure and metabolism may be taxing the energy budgets of tilefish, particularly adult females, with potentially negative impacts on fitness. Environ Toxicol Chem 2019;38:2659–2671. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

The relationship of length-weight and condition factors of layang fish (Decapterus russelli) landed at KUD Gabion of Oceanic Fishing Port, North Sumatra

Fish length-weight analysisis very important to determine the biological conditions of fishand fish stocks so the management of fish sustainability and biodiversity can be easily done.This research aims to determine the biological aspects of the relationship between the length-weight and condition factors of Indian Scad (Decapterus russelli) which landed at KUD Gabion of Oceanic Fishing Port, North Sumatra. The sampling used simple random sampling method conducted from February to March 2019. The number of samples used was 100 sampel. There are two parameters used in this study, namely, the total length of fish (measured from mouth to tip of tail), measured using a ruler with accuracy of millimeters (mm) and the weight of the fish weighed using a digital scale with accuracy of 1 gr. The Data were analyzed by Linear Allometric Model (LAM). The results showed that Indian Scad (Decapterus russelli) had a negative allometric growth pattern with a value of b=2.39. The value of 100.59 from the factors of relative weight conditions indicated a stable state of the water and a value of 3.04 from the factor of Fulton's condition allowed for availabilityabundant food.

Length-Weight Relationship and Condition Factor of Aksu goby, Ponticola turani (Kovačić & Engin, 2008) from Terme Stream (Turkey)

The present study describes the length-weight relationship (LWR) and condition factor of Ponticola turani (Aksu goby) based on 214 individuals from Terme Stream, the northern Turkey. Fish were collected by electrofishing in four different months between June 2015 and August 2016. LWRs of females and males were not significantly different within the same sampling month and among sampling months. The b value of LWR was calculated as 2.86 for females and 2.85 for males. Negative allometric growth was detected in both sexes, without significant difference between their b values. Fulton's condition factor (K) ranged from 0.72 to 1.48 in females and from 0.84 to 1.31 in males; the relative condition factor (Kn) ranged from 0.65 to 1.26 for females and from 0.76 to 1.18 for males. There was a significant difference in mean K of sexes, whereas no considerable difference was detected between their mean Kn. This research reports some biological parameters of Aksu goby for the first time.

Live and frozen Artemia nauplii for catfish Lophiosilurus alexandri (Steindachner, 1876) larvae in different salinities.

The objective of the study was to verify the combination of live and frozen Artemia nauplii, in different salinized water, and its influence in growth and survival of the catfish Lophiosilurus alexandri (Steindachner, 1876) larvae. Larvae were exposed to a combination of two feeds and two different salinities: live Artemia nauplii + 0‰ salinity in the water; live Artemia nauplii + 2‰ salinity in the water; frozen Artemia nauplii + 0‰ salinity in the water; and frozen Artemia nauplii + 2‰ salinity in the water. The experiment was conducted in a randomized design, in a 2 × 2 factorial scheme, 5 replicates, during 15days. The larvae final weight, weight gain, food conversion, standard and total length, biomass, survival, body width, intestinal quotient, Fulton's condition factor, and water quality were evaluated. The use of Artemia nauplii and 2ppm salinized water for L. alexandri larviculture proved to be adequate providing greater growth. This was due to Artemia nauplii being kept alive and attractive for the cultivation of larvae in salinized water, even though salt was a stress factor. Already, the frozen Artemia nauplii was a viable food but should be used preferably in times of lack of live nauplii and without salinization of the water.

ОСОБЕННОСТИ ОБМЕНА ВЕЩЕСТВ В МЫШЕЧНОЙ ТКАНИ ЛЕЩЕЙ ИЗ ИВАНЬКОВСКОГО ВОДОХРАНИЛИЩА

The hydroelectric station in Konakovo is a source of thermal pollution of Ivankovskoye Rreservoir. Its heated waters affect abundance and species composition of hydrobionts. To assess the state of bream there were conducted the studies of the fatness and composition of the end products of metabolism in their muscle tissue. The fish were measured and weighed, their sex and age were determined, and the Fulton and Clark condition factors were calculated. The amount of total water, dry matter, fat, protein, ash and nitrogen-free extractives (NFE) was determined in the muscle tissue of the fish under study. The Fulton and Clark condition factors of bream species from Ivankovskoye Reservoir are higher than those from other reservoirs. On average, fish muscles contained 80.93% of total water, 19.07% of dry matter, 1.04% fat, 15.87% protein, 1.11% ash, 1.05% NFE. According to the fat content in the muscle tissue, the species belongs to the representatives of “lean” fish. Bream species from Ivankovskoye Reservoir are superior to those from Gorky Reservoir in muscle fat, but inferior in the other metabolic characteristics studied. This may be related to less favorable conditions for fish in Ivankovskoye Reservoir in summer compared to Gorky Reservoir. The metabolic indices differed slightly in the muscles of breams of both sexes. Proteins and ash accumulated more intensively in the female muscles. In the muscle tissue of the younger bream groups there was found a higher content of macronutrients than in older bream groups. This can be explained by the habits of fish in the warmed waters.

Assessing Acoustic Tagging Effects on Survival, Growth, and Swimming Ability of Juvenile Lake Sturgeon

AbstractAcoustic telemetry is used to quantify fish movement, ecology, and habitat use and can contribute to assessing the success of species supplementation. In this field, a better understanding of the effects of tag burden (or the impact of an acoustic telemetry tag, which is related to the ratio of tag weight to body weight) is critical to ensure postrelease monitoring. Research on the effects of acoustic tag burden on imperiled fishes at different ontogenic stages, such as juvenile Lake Sturgeon Acipenser fulvescens, is limited. Our study provides key information for the selection of the largest acoustic tag with the greatest battery life possible (taking into account tag burden) to monitor the release success and movements of juvenile Lake Sturgeon stocked for reintroduction. We characterized tag burden effects by examining survival, TL, weight, Fulton's condition factor, and swim performance of individuals. We examined four groups of fish: control (anesthetized and no acoustic tag inserted; n = 24), sham control (anesthetized with incision sutured but no acoustic tag inserted; n = 24), Vemco V8 acoustic tag (2.0 g in air; n = 24), and Vemco V9 tag (4.4 g in air; n = 24). Acoustic tags were inserted into anesthetized fish, and the incision was sutured; tag burden (mean ± SE) ranged from 2.2 ± 0.06% to 4.6 ± 0.10% of total body weight. Results showed that the two tag burden treatments had no significant effects on growth or survival (compared to both control groups) across a 114‐d study period and that critical swim speed at 12–20 d postsurgery was not significantly impacted by increasing tag burden. Because neither of the acoustic tag sizes had significant deleterious effects on the metrics studied, we recommend using a larger V9 tag (i.e., the most powerful tag with the longest battery life) for postrelease monitoring of reintroduced juvenile Lake Sturgeon.

Growth and metabolism of adult polar cod (Boreogadus saida) in response to dietary crude oil

The increasing human presence in the Arctic shelf seas, with the expansion of oil and gas industries and maritime shipping, poses a risk for Arctic marine organisms such as the key species polar cod (Boreogadus saida). The impact of dietary crude oil on growth and metabolism of polar cod was investigated in the early spring (March–April) when individuals are expected to be in a vulnerable physiological state with poor energy stores. Adult polar cod were exposed dietarily to three doses of Kobbe crude oil during an eight weeks period and followed by two weeks of depuration. Significant dose-responses in exposure biomarkers (hepatic ethoxyresorufine-O-deethylase [EROD] activity and 1-OH phenanthrene metabolites in bile) indicated that polycyclic aromatic hydrocarbons (PAHs) were bioavailable. Condition indices (i.e. Fulton's condition factor, hepatosomatic index), growth, whole body respiration, and total lipid content in the liver were monitored over the course of the experiment. The majority of females were immature, while a few had spawned during the season and showed low hepatic lipid content during the experiment. In contrast, males were all, except for one immature individual, in a post-spawning stage and had larger hepatic energy stores than females. Most specimens, independent of sex, showed a loss in weight, that was exacerbated by exposure to crude oil and low hepatic liver lipids. Furthermore, females exposed to crude oil showed a significant elevation of oxygen consumption compared to controls, although not dose-dependent. This study highlights the importance of the energy status of individuals for their response to a crude oil exposure.

Replacement of fish meal with processed carinata (Brassica carinata) seed meal in low animal protein diets of rainbow trout (Oncorhynchus mykiss)

A 56‐day growth trial was conducted to determine the amount of fish meal (FM) in rainbow trout (Oncorhynchus mykiss) diets containing 200 g/kg FM as the sole animal protein source; that could be replaced with carinata (Brassica carinata) meal (CM) processed by aerobic conversion (AC, by fungi ssp.) followed by a single wash (ACCM). ACCM replaced 50, 100 and 150 g of FM. Replacement of ≥100 g of FM with ACCM, resulted in reduced (p < 0.01) growth, due to reduced dietary lysine and diet consumption (p < 0.01). Fulton's condition factor K decreased (p < 0.01) with increased FM replacement. FCR (p < 0.01) had an inverse relationship with diet consumption. The trend in FCR was similar to the trend in PER (p < 0.01). Apparent net protein utilization was lower (p < 0.01) for the highest FM replacement diet. There was no effect of FM replacement by ACCM on whole‐body composition or viscera, spleen and liver weights. However, visceral fat increased (p < 0.01) with increased feed consumption. There was no apparent effect of ACCM on hematocrit, haemoglobin or mean corpuscular haemoglobin contents. Results of this study indicate that replacement of ≥100 g of FM by ACCM in low FM/animal (200 g/kg) RBT diets may have been achieved if feed consumption and dietary lysine were similar.

Growth Disparity in Sympatric Kokanee Breeding Groups

AbstractGrowth is arguably the most important dynamic rate function due to its interaction with survival and recruitment. As such, understanding the mechanisms underlying growth is a primary focus of fisheries research. Kokanee Oncorhynchus nerka in Lake Pend Oreille, Idaho, provide an interesting case study for investigating the factors that influence growth. Early‐run and late‐run kokanee occur in Lake Pend Oreille, but early‐run fish generally grow faster than late‐run fish. The observed growth disparity between early‐ and late‐run fish could be due to genetic differences between the two groups. Conversely, a common hatchery practice of slowing growth by reducing feed has been hypothesized to elicit a compensatory growth response in early‐run fish and to explain the size difference between breeding groups. Using two different experiments, we tested the hypotheses that (1) early‐run kokanee are genetically disposed to grow faster than late‐run kokanee at identical water temperatures; and (2) feed restriction elicits a compensatory growth response in early‐run kokanee that explains the observed size difference between breeding groups. Estimates of mean FL, weight, Fulton's condition factor (K), and specific growth rate (SGR) were not significantly different (P ≥ 0.05) between early‐run and late‐run fish in the first experiment. However, water temperature was positively related to mean FL, weight, K, and SGR for both breeding groups. Fish that were subjected to food deprivation exhibited an increased growth rate and obtained weights similar to those of control fish. Overall, our results suggest that early‐ and late‐run fish have similar growth potential, but certain hatchery practices likely provide early‐run fish with an initial advantage in growth, size, or both.

Impacts of El Niño on the somatic condition of Humboldt squid based on the beak morphology

The Humboldt squid Dosidicus gigas has a short life span, and environmental variability plays a significant role in regulating its population dynamics and distribution. An analysis of 1 096 samples of D. gigas collected by the Chinese commercial fishing vessels during 2013, 2014, and 2016 off the Peruvian Exclusive Economic Zone, was conducted to evaluate the impacts of El Nino events on the somatic condition of D. gigas. This study indicates that the slopes of all beak variables in relation to mantle length (ML) for females were greater than those of males during 2013, 2014, and 2016, and slopes of the upper crest length and the lower rostrum length significantly differed between females and males in 2013 (P 0.05). The Fulton's condition coefficients (K) of females and males in 2013 and 2014 were significantly greater than those in 2016 (P < 0.01). The K values of females were greater than those of males in 2013, 2014, and 2016, and K values significantly differed between females and males in 2013. In normal years, the chlorophyll a (Chl a) concentration showed an N-shaped variability from January to December. However, in the El Nino period, it tended to weaken the upwelling coupled with warm and low Chl a concentration waters. We suggest that the poor somatic condition of D. gigas during the El Nino year was resulted from the low Chl a concentration in the waters, and the abundance of D. gigas would decrease due to the unfavourable environment and the lack of prey items in the El Nino year.

Contaminant accumulation and biological responses in Atlantic cod (Gadus morhua) caged at a capped waste disposal site in Kollevåg, Western Norway

The aim of this study was to assess whether fish in Kollevåg, a sheltered bay on the western coast of Norway, previously utilized as a waste disposal site, could be affected by environmental contaminants leaking from the waste. Farmed, juvenile Atlantic cod (Gadus morhua) were caged for six weeks at three different locations in Kollevåg bay and at one reference location. Sediments and cod samples (bile and liver) were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), per-and polyfluoroalkyl substances (PFASs) and polycyclic aromatic hydrocarbon (PAH) metabolites, revealing a contamination gradient at the four stations. Furthermore, hepatosomatic index (HSI) and Fulton's condition factor (CF) were significantly lower in cod caged closest to the disposal site. Levels and activities of biomarker proteins, such as vitellogenin (Vtg), metallothionein (Mt), and biotransformation and oxidative stress enzymes, including cytochrome P450 1a and 3a (Cyp1a, Cyp3a), glutathione s-transferase (Gst) and catalase (Cat), were quantified in blood plasma and liver tissue. Hepatic Cat and Gst activities were significantly reduced in cod caged at the innermost stations in Kollevåg, indicating modulation of oxidative stress responses. However, these results contrasted with reduced hepatic lipid peroxidation. Significant increases in transcript levels were observed for genes involved in lipid metabolism (fasn and acly) in cod liver, while transcript levels of ovarian steroidogenic enzyme genes such as p450scc, cyp19, 3β-hsd and 20β-hsd showed significant station-dependent increases. Cyp1a and Vtg protein levels were however not significantly altered in cod caged in Kollevåg. Plasma levels of estradiol (E2) and testosterone (T) were determined by enzyme immunoassay (EIA) and showed elevated E2 levels, but only at the innermost station. We conclude that the bay of Kollevåg did not fullfill adequate environmental condition based on environmental quality standards (EQSs) for chemicals in coastal waters. Following a six weeks caging period, environmental contaminants accumulated in cod tissues and effects were observed on biomarker responses, especially those involved in reproductive processes in cod ovary.

Probiotic, antibiotic and combinations in Nile tilapia juveniles culture.

This study aimed to evaluate the effect of the commercial probiotic (Saccharomyces cerevisiae), antibiotic (florfenicol), and its combination for Nile tilapia culture. The experiment was arranged in a completely randomized design with five replications, and five treatments diets: Control: water and diet without additives; YD: yeast in the diet (1 g Kg-1); AW: antibiotic in the water (0.002 g L-1); AWYD: antibiotic in the water, and yeast in the diet (0.002 g L-1 and 1 g Kg-1); and AD: antibiotic in the diet (0.01 g kg-1). The growth parameters as total and standard length, weight, weight gain, biomass, Fulton's condition factor, specific growth rate and plasma cortisol of tilapia did not show the difference between the treatments. The survival rates and food conversion rate of fish were greater in treatment with florfenicol included in the diet. The commercial probiotic did not improve growth or survival. The administration of the antibiotic florfenicol in the water needs more studies. The inclusion of the antibiotic in the diet promotes growth and survival in Nile tilapia juvenile.

Relative condition factor, length-weight relationship and sex ratio of copper mahseer, Neolissochilus hexagonolepis (McClelland, 1839) from Tamor River, Nepal

The present investigation was carried out for establishing the length weight relationship and to enumerate the relative condition factor and the sex ratio of Neolissochilus hexagonolepis from Tamor River, Nepal. Altogether 198 fishes were investigated from December 2014 till the end of November 2016. The sex ratio of the fish was found to be in the ratio of 1:1.2 with female dominating the catch for most parts of the year. Analysis of t-test showed a highly significant relationship (p˂0.05) between length and weight for male, female and sexes pooled. The fish was found to show isometric growth pattern with exponential value (b) equal to 2.962 for sexes pooled. The mean value of Fulton's condition factor (K) for sexes pooled was found to be 1.29 ± 0.49 giving the indication that the general well being of the fish was good. Sudden increase in the value of relative condition factor (Kn) in the size group 30-33 cm in male and 42-45 cm in female indicated their length range during which they showed the sign of maturation for the first time. Steep fall in the value of 'Kn' in size groups 33-36 cm onwards in male and 45-48 cm in female indicated their length range at spent phase.

Reproductive biology ofApocryptes bato(Gobiidae) in the Payra River, southern Bangladesh

The gobioid fish Apocryptes bato (Hamilton, 1822) is a species of mudskipper found in Bangladesh, India, and Myanmar. The reproductive biology of A. bato including sex ratio, size at sexual maturity, breeding season, fecundity, and condition factor was studied in the Payra River, southern Bangladesh during May 2016 to April 2017. A total of 1,028 specimens (303 males and 725 females) were collected. The overall sex ratio was significantly different from the expected value of 1:1 (male: female = 1:2.39, χ2 = 173.23, p < 0.05). Size at sexual maturity was estimated as 4.9 cm standard length. Monthly variations in gonadosomatic index indicate that the main breeding season is from May to December. There was a significant positive correlation of body length and body weight with fecundity. Fulton's condition factor varied in both sexes and was attributed to variations in GSI with maturity. Breeding season was significantly associated with rainfall, but not air temperature. Our findings should improve management and conservation of this fish in the Payra River and surrounding ecosystems.

Population specific sperm production in European flounder Platichthys flesus: Adaptation to salinity at spawning.

Marine teleosts inhabiting the brackish Baltic Sea have adapted to the less saline water with activation of spermatozoa at low salinity hypo-osmotic conditions but with shorter longevity and lower swimming speed that affect the fertilization capacity. Aiming to elucidate if the fertilization capacity may be maintained by increasing the number of spermatozoa produced, testis size for the euryhaline flounder Platichthys flesus with external fertilization was assessed along a salinity gradient; with spawning at a salinity of c. 7, 10-18 and 30-35. Fulton's condition factor K = 0.881 ± 0.085 (mean ± S.D.), 0.833 ± 0.096 and 0.851 ± 0.086, for fish spawning at salinities of c. 7, 10-18 and 30-35, respectively, with no difference between areas, i.e. analysed fish were in similar nutritional condition. A general linear model, with testes dry mass as the dependent variable and somatic mass as covariate resulted in a significant difference between areas-populations with larger testes for P. flesus spawning at a salinity of c. 7 but no difference between fish spawning at a salinity of 10-18 and 30-35. The result suggests that adaptation by increasing the number of spermatozoa produced may be a key mechanism for marine teleosts spawning in areas with low salinities to sustain the fertilization capacity as shown here for the euryhaline P. flesus.