Difference In Standard Length Research Articles

Growth Performance and Survival of Climbing Perch (Anabas testudineus Bloch) Raised in Conventional and Bioflocs System

The aim of this research is to analyze the performance of growth and survival of climbing perch (Anabas testudineus Bloch) which was raised in bioflocs and conventional systems. It investigated the difference in the initial size of the fry stocked with climbing perch has effect. The experimental design used in this study was a Factorial Completely Randomized Design (CRD) with 2 factors and 3 replications: Factor A: climbing perch aquaculture Systems; A1: climbing perch in conventional system of; A2: the climbing perch in bioflocs system; Factor B: Initial Size of fry Stocking; B1: fry size 3 ± 0.5cm; B2: fry size 5 ± 0.5cm and B3: fry size 7 ± 0.5cm. The research was conducted for 90 days with daily growth parameters (SGR), weight and length growth, survival rate, food conversion, flocsvolume density (FVD), and main water quality parameters (water temperature, pH, dissolved oxygen and dissolved ammonia).The results showed that the bioflocs system was able to increase the average growth in the range of 12-67% with an average of 29.73% when compared to conventional systems. The highest value for the daily growth rate or Specific Growth Rate (%/day) was for fry with a size of 7 cm in the bioflocs system (8,419%). The fry size of 3 ± 0.5cm in the bioflocs system had the highest difference in standard length (4.33 cm) while the highest average length during maintenance was the seed size of 7 ± 0.5 cm in the bioflocs system. The survival results of climbing perch fish during the study were based on the highest score on the seed size of 3 ± 0.5cm in the bioflocs system. The survival range of the bioflocs system is 94.89 - 99.67% and that of the conventional system is 82.00 - 94.26%. Thus the bioflocs system is able to increase survival in the range of 5-14% when compared to conventional systems. The bioflocs system is able to provide better feed efficiency than conventional systems in the range of 34-39%. The average value of floc volume density (FVD) in the bioflocs system is in the range of 5.35 – 8.16 ml/L, which is still ideal but can still be improved. Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L. The temperature ranges in the studies on conventional and bioflocs systems are within the acceptable range for fish farming Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L.

Biology of non-native species (Rhaphiodon vulpinus Agassiz, 1829) (Characiformes, Cynodontidae) in a cage fish farm area, Upper Paraná River Basin, Brazil

Abstract Aim To assess the dietary, populational and parasitological aspects of the non-native wild species Rhaphiodon vulpinus in an area under the influence of cage fish farm, in the Ilha Solteira Reservoir, São Paulo State. Methods Fifty-one specimens of R. vulpinus were captured bimonthly, from September 2014 to August 2016, with gill nets with different mesh sizes, in area surrounding a cage fish farm and area not influenced by this activity. The specimens were quantified and their mass (g) and standard length (cm) measured. The stomachs were analyzed with a stereomicroscope and the food items were quantified using the gravimetric method. The parasites were collected during necropsy and their prevalence, mean intensity of infection and mean abundance were subsequently calculated. Results There were changes in feeding activity regarding the area, with greater numbers of individuals with stomach contents in the areas under the influence of fish farm. However, diet composition did not change between the areas analyzed, with prey represented by small fish, such as Geophagus sveni, and shrimps. In the fish farm area there was also a decrease in abundance and an increase in the total mass of the individuals, while there was no difference in standard length between the areas. In terms of parasitological aspects, low parasitic indexes and the absence of differences between the areas were observed. The first report of the monogenean Notozothecium lamotheargumedoi in the Ilha Solteira reservoir is also presented. Conclusions The cage fish farm affected some aspects of the population and the food intake of R. vulpinus. Furthermore, the parasite-host relationship demonstrated that phylogenetic specificities had a greater effect than aquaculture activity on R. vulpinus in the fish farm area.

Age determination and growth pattern of temperate seabass Lateolabrax japonicus in Tango Bay and Sendai Bay, Japan

The temperate seabass Lateolabrax japonicus is a coastal and partial amphidromous fish that is commercially valuable in Japan. Fish age is an important and sensitive variable for stock structure assessment, and inaccurate aging can result in inappropriate management practices. However, there have been few studies on age determination in this species. By examining monthly changes in marginal increment growth, we validated that otolith increments are formed annually. This information was used to develop an age-determination method using otolith sections. Von Bertalanffy growth models were generated based on standard length and weight data for both sexes in Sendai Bay and Tango Bay, Japan. Differences in standard length- and weight-at-age and growth parameters were observed in both sexes and locations. Females exhibited larger standard lengths and weights at older ages than did males, in both locations. Individuals from Sendai Bay exhibited longer average asymptotic lengths, higher asymptotic weight, higher standard length-at-age and higher weight-at-age compared to their counterparts from Tango Bay. Decreases in growth rates in both Sendai Bay and Tango Bay occurred around the age at maturity, indicating that more energy was allocated to reproduction than growth after reaching maturation. Differences between Sendai Bay and Tango Bay in the age at which the maximum instantaneous growth rate and the asymptotic length are reached were thought to arise from differences in water temperature and biological productivity between the two bays.

Uptake Kinetics, Bioconcentration and Debromination of BDE-47 in Juvenile Marine Fish Psetta maxima

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which need more attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t 90 could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28.

Discovery of endangered annual killifish Austrolebias cheradophilus (Aplocheiloidei: Rivulidae) in Brazil, with comments on habitat, population structure and conservation status

Austrolebias genus comprises about 40 small annual killifishes endemic to South America and their highest diversity occurs in southern Brazil and Uruguay, especially in drainages of Patos-Mirim system. Austrolebiasspecies are severely threatened with extinction because their life cycle and restricted ranges. Low dispersal ability and the extensive loss and fragmentation of freshwater wetlands contribute to this threat. Accurate information on the geographic distribution and ecology of the species, vital to plan conservation and management strategies, are scarce. In order to provide basic knowledge for annual fish conservation this paper reports the presence of Austrolebias cheradophilus and present data about its population structure (CPUA, size, sex ratio, length-weight relationships and condition factor) and conservation status in southern Brazil. The estimated CPUA of populations was 0.86 fish/m2. Standard length (SL) of males ranged between 32.14 and 49.17 mm and for females between 25.11 and 41.6 mm. There were no differences in SL between the sexes (t-test = - 1.678; P = 0.105), and Chi-squared test demonstrated marginal differences in proportions of sexes (2.25:1; χ2 = 3.846; P= 0.07). Allometric coefficient of the LWR was slightly hyperallometric (b = 3.08) and K of the specimens ranged from 1.84 to 2.42 (mean ± S.E. = 2.12 ± 0.04). Populations have low density and their biotopes are under critical threat, mainly due to suppression by agriculture, pastures for livestock and increase housing. The species is considered "Critically Endangered" in Brazil, furthermore is strongly recommended its inclusion on lists of endangered fauna and ensures the protection of their remaining habitats.

Underlying causes of habitat-associated differences in size of age-0 walleye pollock (Theragra chalcogramma) in the Gulf of Alaska

Age-0 walleye pollock (Theragra chalcogramma) caught in September in the Gulf of Alaska display habitat-associated differences in standard length (SL). Age-0 fish collected in the region around Sutwik Island and 375 km farther downstream near the Shumagin Islands most likely originate from the Shelikof Strait spawning aggregation. However, age-0 fish resulting from the same spawning aggregation differ in mean size up to 20 mm between areas by September. We examined the otoliths of the larval and age-0 stages of walleye pollock from these two areas in 2000 and 2001 to determine whether growth rate, hatch date, and/or temperature influenced fish size. Circulation models were used to determine whether transport of larvae from an upstream spawning group into the study areas could have occurred. Mean in situ temperature during sampling periods was not defined as a significant factor in altering growth rates. Overlapping hatch date distributions of the larval and age-0 fish in the Shumagin Island area confirmed that the fish were from the Shelikof Strait spawning group. Comparison of hatch date distributions in the upstream Sutwik Island area revealed larger/older larvae from an upstream spawning group mixed with larvae from the Shelikof Strait spawning group. Our results suggest that the offset of 20 mm SL between the groups of age-0 pollock was the result of a combination of enhanced survivorship of early-hatched larvae in the Sutwik area and the introduction and retention of the progeny of another spawning group originating upstream of Shelikof Strait.

Bioconcentration and depuration of endosulfan sulfate in mosquito fish ( Gambusia affinis)

Endosulfan is an insecticide which has been widely used in agriculture. The technical grade material consists of two isomers (alpha and beta). Under natural environmental conditions, endosulfan is metabolized through oxidation and the main metabolite in the environment is endosulfan sulfate. Most ecotoxicology research has been conducted with technical grade endosulfan to determine effects on non-target aquatic organisms. Little data on the effects of endosulfan sulfate on aquatic organisms are available in the literature. This study characterizes endosulfan sulfate bioconcentration and depuration in mosquito fish ( Gambusia affinis). During the study, G. affinis was exposed to an environmentally relevant endosulfan sulfate concentration of 0.25 μg L −1 for 5 weeks (uptake phase) followed by a 3-week period (depuration phase) in clean water. This study found that G. affinis bioconcentrated endosulfan sulfate. During the exposure phase, fish tissue concentrations of endosulfan sulfate increased with time up to 730 μg kg −1 dw or 215 μg kg −1 ww. The bioconcentration data followed Michaelis–Menten kinetics better than the one-compartment first order kinetics (1-CFOK). Using these models, the bioconcentration factors for endosulfan sulfate-exposed G. affinis were from 687 to 888 L kg −1 in wet weight or 2263 to 2936 L kg −1 in dry weight. During the depuration phase, endosulfan sulfate concentrations in tissue significantly decreased and the data followed first order kinetics. The half-life of endosulfan sulfate in G. affinis was about 9 d. There was no significant difference in standard length or weight between control and exposed fish. The growth data followed the von Bertalanffy growth model. However, the condition factor of exposed fish increased with time during the exposure phase.

Effect of catch‐and‐release angling on growth and survival of rainbow trout, Oncorhynchus mykiss

Abstract Catch‐and‐release angling is popular in many parts of the world and plays an increasingly important role in fish conservation efforts. Although survival rates associated with catch‐and‐release angling are well documented for many species, sublethal effects have been less studied. An experiment was conducted to directly assess the effects of catch‐and‐release angling on growth and survival of rainbow trout, Oncorhynchus mykiss (Walbaum). Catch‐and‐release events were simulated in laboratory tanks maintained at 15–16 °C with hooks manually placed in pre‐designated locations in the mouths of the fish. There were no differences in standard length (P = 0.59) or wet weight (P = 0.81) gained between caught and uncaught fish over a 1‐month angling and recovery period. Survival was 96.99 ± 0.06% for rainbow trout caught and released, and did not vary with number (one, two or four) of captures. Thus, catch‐and‐release angling appears to have little effect on growth and mortality of rainbow trout hooked in the mouth.

Merging social hierarchies: Effects on dominance rank in male green swordtail fish (Xiphophorus helleri)

When the same set of individuals are placed in different social contexts, some groups members often experience a change in dominance status. We examined the context-dependence of social status using a group fusion protocol in male green swordtail fish (Xiphophorus helleri). Six individuals were matched for size and separated into two groups of three fish. Each triad established a stable hierarchy after which time the two subgroups were merged into one larger assemblage. The maintenance of within- and between-group rank relationships was examined. Relative rank was preserved within each subgroup across social contexts but we found no evidence that familiarity with dominant animals assists individuals of one subgroup in achieving higher rank (coat-tail effects). Dominant individuals from the pre-fusion groups were significantly likely to obtain high status in the merged group and vice versa for subordinate pre-fusion animals. These results demonstrate that social rank in swordtails is relatively impervious to changes in social context, but we address some deviations from this trend. Small differences in standard length were a significant predictor of the most dominant rank in the post-fusion hierarchy, with the largest animals tending to occupy the alpha position. We discuss our results in terms of the potential factors involved in within- and between-group rank maintenance, including individual recognition, winner and loser effects, or asymmetries in dominance-related characteristics.

Responses of cobia Rachycentron canadum larvae to abrupt or gradual changes in salinity

Cobia Rachycentron canadum has recently been recognized as a potential candidate for aquaculture because this species exhibits high growth rates during the larval and juvenile stages. A series of salinity tolerance tests were performed on larval cobia in order to identify the salinity requirements of this species during culture. The effect of spawning salinity on larval tolerance is also discussed. The 18-h survival of cobia larvae 3, 5, 7 and 9 days post-hatch (dph) following abrupt transfer to salinities ranging from 4 to 48 ppt was evaluated using logistic regression. The salinity range within which 90% of the larvae would be expected to survive appeared to be age-dependent and was narrowest at 3 dph (20.1–35.6 ppt) and wider at 7 and 9 dph (7.5–32.8 ppt). The 18-h tolerance of larvae to abrupt changes in salinity was unaltered by spawning salinities of 28.0 and 36.5 ppt. In the second part of the study, rearing salinities were dropped by 5 ppt day − 1 from 32–34 ppt (control) to 5, 10, 15 and/or 20 ppt beginning on 1, 4, 7, 10 or 13 dph. Larval survival from hatching through 10 days following the initial drop in salinity was significantly ( P < 0.05) lower (< 2%) in the low salinity treatments than the control (12–15%) when the salinity drop was initiated 1 and 4 dph. No significant differences in larval survival were detected between the control (12.5%) and 20 ppt treatment (8.9%) when the salinity drop began on 7 dph but survival in the 10 ppt treatment (3.2%) was significantly lower than the control. When the salinity drop was initiated on 10 dph, no significant differences in survival (10.7–14.7%) were detected among treatments. Finally, no significant differences in survival (9.6–15.4%) were found when the salinity drop was initiated 13 dph and terminated 22 dph. However, when a similar study was extended to 28 dph survival from 13 to 28 dph was significantly lower in the 5 (49.4%) and 10 (72.5%) ppt treatments than the control (96.5%) due to disease. No significant differences in standard length were observed for larvae within each experiment irrespective of rearing salinity. The results of this study indicate that rearing cobia larvae in salinities as low as 15 ppt may be possible beginning 13 dph.

Female Size Influences Mate Preferences of Male Guppies

AbstractGuppies (Poecilia reticulata) have a promiscuous mating system in which female choice for brightly coloured males plays an important role. Consequently, much research on guppies has examined how mate choice by females has lead to the evolution of male colour patterns. Much less attention has been devoted to mate choice by males in this species. In this study, we show that male guppies are choosy when selecting a female to associate with, significantly preferring the larger female when presented with two females that differed by ≥2 mm in standard length (SL). The strength of their preference for each female increased with absolute female size. The relative sizes of the females, however, also influenced male mating preferences: males showed stronger preferences for the larger female as the difference in SL between the two females increased. Such a preference for larger females is not unexpected as fecundity generally increases with body size in female fish. Thus, males choosing to mate with the larger female should have higher reproductive success. An apparent, but non‐significant anomaly, whereby males appear to prefer the smaller of the two females when the difference between female SL was &lt;4 mm, deserves further investigation.

Sexual Dimorphism in Plains Minnow,Hybognathus placitus

Abstract Hybognathus placitus collected from several west Texas streams exhibit sexual dimorphism in body form, which is unusual in cyprinids. Seventeen morphological measurements, including standard length, were made on 62 specimens and analyzed for sexual dimorphism. Partial warp scores were used to describe sexual dimorphism in body shape. There was no difference in standard length between males and females (ANOVA, P = 0.9038, F1,60 = 0.0147), but there was a highly significant (MANOVA, F1,60 = 4.78, P < 0.001) sexual dimorphism in body shape. Overall, males have relatively longer first dorsal fin rays, larger heads, and caudal peduncles, whereas females are deeper bodied and have relatively longer trunks, from the pelvic fin insertion to the anal vent. Differences between male and female H. placitus in length of the first dorsal fin ray are readily apparent and can potentially be used for field identification.

Feeding ecology of silverperch, Terapon plumbeus Kner, and the impact of fish-pens in Laguna de Bay, Philippines

Summary Aquaculture is an important factor in the fishery of Laguna de Bay in the Philippines; fish-pens and net-cages covered ≈10% of the lake surface in the late 1990s. The present study was carried out to assess the possible influences of aquaculture on a wild fish species, silverperch, Terapon plumbeus Kner, with a special emphasis on the feeding ecology of this fish. For the purposes of the investigation, 24-h samples were taken at 2-month intervals close to a fish-pen as well as in open water over a one-year period to acquire more information on this species. Significant differences in standard length and total weight were found between stations and sampling months. In open water, a mean standard length of 53.6 mm and a mean total weight of 4.2 g were found, whereas close to the fish-pen, the corresponding values were 57.6 mm and 5.4 g, respectively. The maximum mean standard length was attained around December 1996 and February 1997 (59.5 mm in open water; 66.1 mm close to the fish-pen), and the minimum was found in June 1996 (49.1 mm in open water; 46.2 mm close to the fish-pen). Noticeable differences were found in the food spectrum between the two sampling stations. Zooplankton, the major food source at both stations, was more important in the stomach content of fish in open water. The same was true for insects (i.e. chironomid larvae), although these did not make up such a large fraction of the diet. On the other hand, close to the fish-pen, aufwuchs-algae, phytoplankton and fish were more important. Generally, benthic organisms were consumed more frequently close to the fish-pen. Zooplankton was more important in the diet of smaller fish. In all size groups, the importance of zooplankton decreased during the rainy season.

Coexistence of Anadromous and Resident Life History Styles of Pond Smelt, Hypomesus nipponensis, in Lake Ogawara, Japan, as determined by Analyses of Otolith Structure and Strontium:Calcium Ratios

Anadromous and resident forms of pond smelt, Hypomesus nipponensis, were found to occur in sympatry in Lake Ogawara, Japan. Profiles of Sr: Ca ratios from individuals could be grouped to two patterns (1) a ‘resident’ pattern with low Sr: Ca ratios from core to edge and (2) an ‘anadromous’ pattern with relatively low Sr: Ca ratios near the core with abrupt increases in ratios at a location approximately 0.3 mm from the core. Spawners smaller than 60 mm standard length (SL) were resident, between 60 to 80 mm were mixed resident and anadromous, and larger than 80 mm were anadromous. Anadromous individuals first migrated after 40 to 82 days from hatching (mean±sd, 59.1±13.5 d) and 14.6 to 30.9 mm SL (22.2±5.3 mm). There was no difference in SL between resident and anadromous individuals during age at first migration, suggesting that size may not be the mechanism for divergence of alternative life history styles.

Patterns of pair formation in protandrous anemonefishes,Amphiprion clarkii, A. frenatus andA. perideraion, on coral reefs of Okinawa, Japan

At Sesoko Island, stocks of anemonefishes were observed for 2 years in a 350 m × 150 m area where host sea anemones were sparse. About 40% of the pairs separated, mostly due to typhoon attacks or displacement. Widowed mates remained and acquired new mates on the same sea anemone, except for one case. New mates were immigrant adults inAmphiprion clarkii and A.frenatus, but resident juveniles inA. perideraion. A. clarkii andA. frenatus moved between sea anemones and sometimes displaced smaller consexuals, butA. perideraion rarely moved. The difference in mobility among the 3 species was related to the mean difference in standard length between the largest juveniles in breeding groups and the minimum size of breeding males in each species, and that between breeding males and the minimum size of breeding females. InA. perideraion both of these differences were small, so pairs could be formed quickly by residents after mate loss. On the contrary, inA. clarkii andA. frenatus, either or both differences were large and it would take a longer time to form a pair after mate loss. Differences in mobility affected the patterns of pair formation, and then the size composition of members in breeding groups.

Mate Choice by the Male Convict Cichlid (Cichlasoma nigrofasciatum; Pisces, Cichlidae)

AbstractThe influence of standard length (SL) and maximum body width on the attractiveness of female to male convict cichlids was examined in a choice apparatus. Preliminary experiments showed that maximum body width (abdominal swelling), ovary mass and ovary volume of females increased significantly over the 7‐d post spawning period. Variation in body width explained a moderate amount of the variation in ovary mass and volume. Therefore, body width is a suitable indicator of gravidity. Male convict cichlids were offered a simultaneous choice between two females that varied in standard length (SL) and/or gravidity. Choice was determined by amount of time the male spent near each female. Males chose the larger of two females when both were gravid but showed no choice when neither was gravid. In general, males chose the gravid female when one was gravid and the other was not, regardless of the difference in SL between them. Choice of female by males was not influenced by female behaviour in the test apparatus. We suggest that mate choice by convict cichlid males is based primarily on female gravidity and secondarily on female SL.

Comparison of Live Brine Shrimp Nauplii and Nonliving Diets as First Food for Striped Bass Larvae

Abstract A feeding experiment was conducted in aquaria to evaluate growth, survival, and food consumption by larval striped bass (Morone saxatilis) fed live brine shrimp, shock-frozen brine shrimp, freeze-dried brine shrimp, or a commercial dry diet. The larvae were fed from first feeding through day 19 posthatch. Through day 16 there was no difference in standard length between fish fed the live brine shrimp and those fed the dry diet (P > 0.05), whereas fish fed the other diets were smaller (P < 0.05). At day 19, the striped bass fed the live brine shrimp were larger than those fed all other diets (P < 0.05). Survival was greatest (P < 0.05) for fish consuming live brine shrimp (28.5%), followed by those fed the dry diet (18.0%), freeze-dried brine shrimp (9.8%), and shock-frozen brine shrimp (9.3%). The percentage of fish consuming food was greatest (P < 0.10) for striped bass fed live brine shrimp (85.8%), followed by those fed freeze-dried brine shrimp (38.6%), shock-frozen brine shrimp (38.2%), and ...

Recognition of cohorts and growth of larval and juvenile roach Rutilus rutilus (L.), using size‐class ordination of developmental steps

Roach larvae and 0+ juveniles were sampled weekly in three different floodplain channels (stagnant, semi‐lotic, lotic) of the Upper Rhône River, France, from spring to autumn 1985 using Point Abundance Sampling by electrofishing. Length‐frequency analysis by size‐class ordination of developmental steps successfully distinguished both overlapping and non‐overlapping histograms within the data matrix and revealed the temporal and spatial segregation of a number of cohorts, individuals born at a common site on the same day, which in some cases presented significant differences in standard length within a given developmental step. Despite these initial differences, the various cohorts converged to form one relatively homogeneous cohort around the moment of transition to the juvenile period. Significant differences in standard length were found between populations in the open lotic channel (relatively cooler) and those in the closed, stagnant (relatively warmer) former channel, suggesting that fish growth in isolated ecosystems is influenced by higher or periodically elevated temperatures and by greater levels of resource competition and predation. A similar pattern of differences in length was also observed in 0+ juvenile roach collected from 18 other floodplain channels of the Upper Rhône.

Comparative Hematology of Lepomis microlophus and Cichlasoma cyanoguttatum

sunfish, Lepomis microlophus (Centrarchidae), and the Rio Grande perch, Cichlasoma cyanoguttatum (Cichlidae), from Hidalgo County, Texas, was studied from October 1974 to December 1975. There were no significant differences between the sexes in either species, but both species exhibited significant variation in blood parameters due to differences in standard length, reproductive condition or season. Change in reproductive condition apparently affected erythrocyte size. Seasonal changes in hemoglobin concentration and erythrocyte dimensions of L. microlophus were consistent with a pattern of increasing values with increasing water temperature. Erythrocyte size in C. cyanoguttatum may decrease with increasing water temperature. Hemoglobin concentration of the two species was similar, but L. microlophus had a larger number of erythrocytes and less hemoglobin per erythrocyte than C. cyanoguttatum. Comparative data suggest that the magnitude of difference in the hematology of L. microlophus and C. cyanoguttatum is no greater than that which exists between species of Lepomis.

Growth and form in fossil rhipidistian fishes (Crossopterygii)

A study is presented of the patterns of growth in Devonian fossil Rhipidistia, particularly Eusthenopteron foordi Whiteaves. Significant changes in basic anatomical characteristics including certain cranial proportions and the relative position of insertion and shape of the fins may be correlated with differences in standard length. These differences result from various types of differential growth. Growth markings on the scales indicate that the“juvenile”condition may last through two seasons of growth. The differences in body configuration are interpreted as being fully adaptive and related to important differences in locomotor patterns and ecology. The results of the study suggest that the rhipidistian fish formerly known as“Thursius ? clappi”Romer is a juvenile and a re‐interpretation of this form is given.