Silver Perch Research Articles

Production of the Australian freshwater silver perch, Bidyanus bidyanus (Mitchell), at two densities in earthen ponds

Silver perch fingerlings (mean weight 15.3 g) were stocked at densities of 21 000 and 7000 fish/ha in six 0.1-ha earthen ponds and cultured for 10 months. There were three replicate ponds for each density. Ponds were aerated for at least 11 h a day and water was added every 4 weeks to replace that lost by evaporation and seepage. Fish were fed a formulated diet containing 35% crude protein at 4% body weight per day for the first 4 weeks and at rates up to 3% thereafter. The mean annual production rate of 9819 kg/ha of fish stocked at 21 000/ha was significantly higher ( P < 0.01) than the annual rate of 3699 kg/ha of fish stocked at 7000/ha. The maximum daily production and growth rates achieved in any pond over a 1-month period during summer were 97.7 kg/ha and 5.1 g/fish, respectively. Stocking density did not significantly ( P > 0.05) affect survival rate (treatment means for 21 000 and 7000 fish/ha: 92.8 and 94.7%), daily growth rate (0.2–3.3 and 0.3–3.4 g/fish), weight at harvest (434.9 and 473.2 g), food conversion ratio (1.9:1 and 1.8:1) and cost of feeding ($A1.55 and $A1.47/kg), suggesting that higher stocking densities and production rates are possible. Water temperatures ranged from 11.1 to 30.0 °C. Significantly ( P < 0.05) slower growth during December was associated with concentrations of NH 3-N up to 0.65 mg/l. The results demonstrate that silver perch is an excellent species for semi-intensive culture in static earthen ponds with the potential to form the basis of a large industry in Australia, based on high-volume, relatively low-cost production.

Salinity tolerance and osmoregulation in the silver perch, Bidyanus bidyanus Mitchell (Teraponidae), an endemic Australian freshwater teleost

Juvenile silver perch, Bidyanus bidyanus, were subjected to direct transfer from fresh water to various test salinities. No mortality was observed when the fish were transferred from fresh water to a salinity of 12, but 40% mortality was observed at a salinity of 15 after seven days. Pre-acclimation of silver perch to a salinity of 12 for seven days resulted in only marginally better survival at higher salinities. Plasma osmotic concentrations of silver perch rose slightly in salinities below 9 but rapidly at higher salinities, following the same track as the iso-osmotic line. Minimum body water content was observed in individuals subjected to a salinity of 15 for 24 h. As found in other freshwater teleosts, chloride cells were found in the branchial epithelium of silver perch. Accessory cells were observed beside the chloride cells in both freshwater and salt-water conditions. Fish subjected to a salinity of 12 for seven days showed chloride cells with a more developed tubular system than controls. The length of the junctions between chloride cells and accessory cells was significantly shorter in fish adapted to a salinity of 12 than in controls. The ultrastructural feature of 'interdigitations' of accessory cells was not observed during salt-water adaptation. These data indicate that silver perch is the least tolerant of high salinities and the most truly freshwater Australian teleost species examined to date.

Restriction endonuclease analysis of atypical Aeromonas salmonicida isolates from goldfish Carassius auratus, silver perch Bidyanus bidyanus, and greenback flounder Rhombosolea tapirina in Australia

Restriction endonuclease analysis of atypical Aeromonas salmonicida isolates from goldfish Carassius auratus, silver perch Bidyanus bidyanus, and greenback flounder Rhombosolea tapirina in Australia

Use of temperature to manipulate circulus patterns on scales of silver perch,Bidyanus bidyanus(Mitchell), for the purpose of stock discrimination

Controlled temperature variation was used to induce marks on scales of silver perch, Bidyanus bidyanus (Mitchell), for stock identification. Genetically similar fish were held in tanks at three temperatures for a period of 4 weeks. Circulus spacing information was acquired using automated video digitizing equipment. Discriminant function analysis was used to classify fish into their respective rearing temperatures. Fish held at 30°C were classified with high accuracy (94–96%). Classification inaccuracies increased in fish held at the lower temperatures. Fish growth at each temperature was examined and classification accuracies were a reflection of growth differences. The use of temperature variables to induce marks on scales offers scope for batch-marking pre-stocked fish.

Preliminary Evaluation of the Australian Freshwater Fish Silver Perch,Bidyanus bidyanus,for Pond Culture

Silver perch, Bidyanus bidyanus, were stocked into two 0.4-ha earthen ponds at densities of 2,788 fish/ha (Pond 1) (mean weight = 7.4 g.) and 14,500 fish/ha (Pond 2) (mean weight = 2.5 g.). Fish were fed a commercial trout diet (50% protein) at daily rates of up to 3% body weight. Within 2 weeks after stocking, fish were feeding aggressively at and near the surface. In Ponds 1 and 2, survival rates were 97.5% and 73.5%, and mean weights were 116.5 g. and 202.o g. after 117 and 181 days, respectively. Water temperatures ranged from 22.0 and 31.3°. The food conversion ratio was 0.7 in both ponds. These results, achieved with no supplemental aeration or water exchange suggest that silver perch has potential for intensive culture in earthen ponds in Australia.

Influence of light intensity and wavelength on phototactic behaviour of larval silver perch Bidyanus bidyanus and golden perch Macquana ambigua and the effectiveness of light traps

Larval golden perch, Macquaria ambigua, and silver perch, Bidyanus bidyanus, were exposed to light gradients in wavebands centred on 400, 496, 601 and 695 nm at nominal quantum irradiance values of 0–1, 1–0 and 10 μmol m−2 s−l. Silver perch larvae displayed stronger phototactic behaviour than golden perch, and both species were most responsive to light in the 601 nm waveband. The intensity of phototactic responses in both species was greater at higher irradiance levels. Enhanced responsiveness to longer wavelengths reflects possible adaptations to life in turbid habitats where the underwater light field is dominated by yellow/orange wavebands.At night, traps fitted with 12 h yellow lightsticks attracted more golden perch larvae than traps with blue, green, orange, red or no lightstick. The efficacy of yellow lightsticks may be due to yellow/orange wavebands not being attenuated under water as rapidly as blue or red wavebands. Yellow lightsticks also emit a greater intensity of light over a longer time than other colours tested, which may have increased the effectiveness of yellow traps. Light traps were ineffective during the day.

Influence of light intensity and wavelength on phototactic behaviour of larval silver perch Bidyanus bidyanus and golden perch Macquaria ambigua and the effectiveness of light traps

Influence of light intensity and wavelength on phototactic behaviour of larval silver perch Bidyanus bidyanus and golden perch Macquaria ambigua and the effectiveness of light traps

Swimming ability of adult golden perch, Macquaria ambigua (Percichthyidae), and adult silver perch, Bidyanus bidyanus (Teraponidae), in an experimental vertical-slot fishway

The swimming abilities of adult golden perch, Macquaria ambigua (Richardson) (Percichthyidae) (441�16 mm, mean total length+s.d.), and adult silver perch, Bidyanus bidyanus (Mitchell) (Teraponidae) (258 �10 mm, mean fork length � s.d.), were tested in an experimental vertical-slot fishway. These two Australian species are potamodromous, and the adult fish move upstream large distances. Golden perch readily used the vertical-slot fishway, and a 20-min NV90 (the maximum water velocity that 90% of the fish in a sample can negotiate in 20 min) of 1.83 m s-1 (95% confidence limits 1.43-2.03 m s-1) is recommended for fishway design in the Murray-Darling river system. This velocity equates to a 171-mm step height between fishway pools and should be applied to a minimum pool size of 3 m (length) by 2 m (width) to avoid excessive turbulence. Lower velocities and larger pools might be necessary for long fishways or where there are large migrations of fish. Some silver perch used the fishway, but the results for this species were inconclusive. Fish were re-used at different velocities during the experiment, and a learning trial indicated that the number of fish negotiating the fishway increased with repeated use of the fish.

Discrimination between hatchery stocks of silver perch, Bidyanus bidyanus (Mitchell), using scale growth patterns

Abstract. A study to develop techniques for assigning cultured silver perch, Bidyanus bidyanus (Mitchell), to their hatchery of origin was conducted using scale growth patterns. Automated video digitizing equipment was used to acquire circuli spacing information. Discriminant function analyses were then used to classify pond-raised fish to their hatchery of origin with up to 91% accuracy. One batch of fish was raised under controlled conditions indoors in a tank to manipulate formation of scale growth patterns. When compared with pond-raised fish, separation was up to 99% accurate. This technique offers scope [or efficient batch marking of pre-stocked fish, thereby improving the ability of managers to evaluate stocking programmes.

Effect of salinity on the development of silver perch ( Bidyanus bidyanus) eggs and larvae

1. 1. Silver perch eggs were transferred into different salinities at selected times post-fertilization. Hatching rate depended on transfer time. Eggs transferred within 1 hr post-fertilization had a lower hatching rate than those transferred after 1 hr. No larvae hatched when the salinity exceeded 18 ppt and all larvae hatched from water with a salinity above 9 ppt died within 4 days. 2. 2. At a salinity of 6 ppt, eggs transferred at an early stage (20 min and 1 hr post-fertilization) had a much lower survival rate than those transferred at 5, 11 and 16 hr post-fertilization. This effect may depend on the water hardening process of silver perch eggs. 3. 3. Larvae hatched at a salinity of 6 ppt showed a better survival rate than those hatched in freshwater during the first 20 days post hatching. This effect may be due to the inhibition of microbial pathogens by saline water.

Evaluation of coded wire tags for marking fingerling golden perch, Macquaria ambigua (Percichthyidae), and silver perch, Bidyanus bidyanus (Teraponidae)

Trials were conducted to evaluate coded wire tags for marking hatchery-produced golden perch and silver perch fingerlings prior to their release into the wild. Two size classes of fish were tagged: 'small' fish were 21-39 mm in total length and 'large' fish were 50-71 mm in total length. Tags were implanted into either the cheek muscle or the snout. Tagging rates were 200-548 fish h-1. Although tag retention in large cheek-tagged golden and silver perch was 100% after 30 days, rearing fish to this size was not practical. Retention rates for small cheek-tagged golden perch (94%) and silver perch (100%), the usual size of fingerlings when released to the wild, were considered to be sufficient for a tagging programme. Retention of tags in the snout was poor; only 6% of golden perch and 48% of silver perch retained tags after 30 days. Most cheek-implanted tags that were shed by fish during long-term tag-retention trials were lost in the first four months. With the exception of silver perch in one trial, which were infested by Ichthyophthirius multtfiliis, survival of tagged fish was 95-100% after 30 days. Factors affecting tag retention and survival of tagged fish, including fish size, tagging site and operator experience, are discussed. The results indicate that coded wire tags are a potential means of marking golden and silver perch fingerlings prior to stocking. Their use will assist fisheries managers in the assessment of the contribution of stocking programmes to commercial and recreational fisheries.

Limnology of rearing ponds for Australian fish larvae: Relationships among water quality, phytoplankton, zooplankton, and the growth of larval fish

Fertilization of earthen ponds used to rear the larvae of golden perch, Macquaria ambigua, and silver perch, Bidyanus bidyanus, resulted in phytoplankton blooms dominated by the cyanobacterium Anabaena possibly because of a low N:P ratio. There was a zooplankton succession of rotifers (mostly Brachionus), Moina, Boeckella and Mesocyclops, and then Daphnia. An increase in Daphnia correlated with a decline in Anabaena, suggesting grazing on that cyanobacterium. Golden perch larvae included copepods in their diet whereas silver perch did not, and this was reflected in lower Boeckella numbers in the golden perch ponds. There was sufficient zooplankton forage, supplemented by chironomid larvae in the later stages of the rearing ponds, for fish growth. The limnological conditions and zooplankton communities in these ponds provide a model for evaluating nursery grounds for these fish.

Toxicity of endosulfan to native and introduced fish in Australia

AbstractSemistatic bioassays of endosulfan with native and introduced Australian fish indicated that they are sensitive to this insecticide at low concentrations. The introduced European carp (Cyprinus carpio) was the most sensitive species, with a measured 96‐h LC50 of 0.1 μg/L, whereas the native eastern rainbow fish (Melanotaenia duboulayi) and silver perch (Bidyanus bidyanus) were the least sensitive, with measured 96‐h LC50 values of 2.4μg/L. The measured 96‐h LC50 values of endosulfan for bony bream (Nematolosa erebi), golden perch (Macquaria ambigua), and rainbow trout (Oncorhynchus mykiss) were 0.2, 0.5, and 1.6 μ/L, respectively. Toxicities of endosulfan in Sydney mains water and Mehi River water were similar when rainbow fish, golden perch, and silver perch were used as test animals. The initial measured concentration was about 42% of the nominal concentration, whereas final measured concentration after 24 h in semistatic tests declined to 5.6% of the nominal concentration. The toxicity of endosulfan was similar in Australian native and introduced fish and in overseas fish, but varied markedly with test method. The 96‐h LC50 values for one species, the rainbow fish, varied from 0.5μg/L when reported as measured concentrations in a flow‐through test to 11.4 μg/L as nominal values in a static test. These differences span much of the variation found in 96‐h LC50 values for all fish species described in the world literature.

Use of Cellulose Acetate Electrophoresis and Nondestructive Sampling Procedures for Identification of Potential Gene Markers

Abstract Five species of freshwater fish that are native to Australia and are currently used for aquaculture or are being considered for future development as cultured species – golden perch (Macquaria ambigua), silver perch (Bidyanus bidyanus), spangled perch (Leipotherapon unicolor), Murray cod (Maccullochella peeli), and dewfish (Tandanus tandanus) – were sampled for cellulose acetate gel electrophoresis. Baseline data on enzyme loci were produced to detect which ones have potential use as gene markers. Twenty-six enzymes were screened for each of the five species, and the specific electrophoretic running conditions resolved 40 enzyme loci. Three types of tissue that did not require destructive sampling were examined (fin tissue, white muscle, and body mucus) to assess whether the products of enzyme loci could be detected. Some of the enzyme loci described from liver, white muscle, and eye tissues were resolved from each of these three tissues that can be nondestructively sampled. Thus, these tissues c...

Validation of Daily Increment Formation in the Otoliths of Juvenile Silver Perch, Bairdiella chrysoura

Otoliths of juvenile silver perch were marked by immersing live fish for 3 h in a calcein-seawater solution. Calcein produced a fluorescent mark on the sagittal otoliths that was visible under ultraviolet light. The hypothesis of one increment per day was tested by regressing the number of otolith increments that formed after marking on the number of days that fish were held in lab and field experiments. Silver perch formed one increment per day under nearly all conditions. Salinity (15‰ or 30‰) and dietary ration (4% or 10% body weight d−1) were varied among experimental groups of lab-reared fish. The short-term effect of low rations appears primarily as interrupted formation of otolith increments: fish fed 10% body weight d−1 formed one increment per day but fish fed 4% d−1 averaged less than one increment d−1. Reduction in increment formation occurred despite no significant difference in average width of otolith increments or apparent condition of silver perch over the 20-d experiment. Salinity effects were difficult to interpret: salinity interacted with ration to modify increment formation but did not independently alter the daily rate of increment formation. This novel interaction among ration and salinity is not well understood and warrants additional study. In silver perch, otolith growth appears responsive and sensitive to local environmental conditions. This responsiveness confirms the need for validation of increment formation across the range of environmental conditions that fish are likely to encounter. It also suggests that otolith structure may contain detailed information about the life history of individual silver perch.

Use of Common Salt to Treat Ichthyophthiriasis in Australian Warmwater Fishes

Abstract Four species of Australian warmwater fishes were treated for ichthyophthiriasis with 5 g common salt/L. Juvenile silver perch (Bidyanus bidyanus), golden perch (Macquaria ambigua), Murray cod (Maccullochella peeli), and catfish (Tandanus tandanus) recovered from infestations of Ichthyophthirius multifiliis within 2 weeks. All fish in the control treatments died. The treatment eliminated the theronts and trophonts from all host fish by day 7 within the temperature range 19–26°C and by day 14 within the temperature range 11–18°C.

Clinotactic responses of Larval Silver Perch (Bidyanus bidyanus) and Golden Perch (Macquaria ambigua) to simulated environmental gradients

Larval silver perch (Bidyanus bidyanus) and golden perch (Macquaria ambigua) were subjected to gradients of light, depth, flow and wood leachate from river red gum (Eucalyptus camaldulensis) as well as a control treatment with no gradient. Both species were strongly attracted to light, while golden perch larvae were also attracted to river red gum and were carried downstream by water flow. Neither species displayed any response to depth. Gradient responses of silver perch were significantly more variable (P &lt; 0.05) than those of golden perch, which may result in silver perch larvae being more widely distributed in floodplain habitats. Golden perch larvae may be more closely associated with inundated river red gum than silver perch larvae.

Chronic inflammatory cells with epithelial cell characteristics in teleost fishes.

Certain cells that participate in the chronic inflammatory response of teleost fishes have many features typical of epithelioid cells of mammals. Such features include high metabolic activity, frequent phagolysosomes, and cytoplasmic interdigitations between adjacent cells; however, the epithelioid granulomas formed in response to certain diseases in teleost fishes also have several features associated with epithelial cells. Cases of ulcerative mycosis or acid-fast bacterial infection in Atlantic menhaden (Brevoortia tyrannus), fungal infection in silver perch (Bairdiella chrysoura), and mycobacteriosis in Mozambique tilapia (Oreochromis mossambicus) had epithelioid cells that were joined together by well-formed desmosomes with tonofilaments. "Mature granulomas" of the ulcerative mycosis-infected menhaden stained positively for cytokeratin, a cytoskeletal protein that is considered to be highly specific for epithelial cells. The consistent presence of these heretofore unrecognized epithelial features suggest that they may be characteristic of certain types of cells participating in piscine chronic inflammation.

Effect of dietary lipid on the fatty acid composition of silver perch (Leiopotherapon bidyanus) lipids

1. 1. Silver perch reared on high fat diets accumulated significantly more body fat than those reared on fat free diets. 2. 2. Dietary fatty acids accumulated in both the depot lipids and phospholipids of the fish. 3. 3. On transfer from a high fat diet to a fat free diet, there was a preferential incorporation of both arachidonic ( 20:4(n-6) ) and docosahexenoic ( 22:6(n-3) ) acids into phospholipids during lipid turnover. 4. 4. It was concluded that silver perch have a dietary requirement for fatty acids of both the ( n-3 ) and ( n-6 ) series.

The hormone-induced spawning of silver perch, Bidyanus bidyanus (Mitchell) (Teraponidae)

Adult silver perch, Bidyanus bidyanus, were induced to spawn by the injection of human chorionic gonadotrophin (HCG) or a preparation of the pituitary gland from common carp (CPG). Males, injected with 200 IU/kg HCG, were placed with injected females in 2000-l concrete tanks, and spawning occurred 31–40 h after injection at a water temperature of 25°C. All females injected with 200 IU/kg HCG spawned completely, and the mean hatch rate of eggs was 88.8%. Higher dosages of HCG, and the use of CPG, resulted in reduced spawning success and, in general, lower mean hatch rates. Techniques for egg incubation are briefly described.