Goldfish Eggs Research Articles

Study on the Short-Term Preservation of Gametes, Cross-Stimulation of Oocytes by Distant Sperm, and the Impact of Cold-Stimulated Fertilized Eggs on Eyes in the Celestial Goldfish

This study layed the groundwork for the creation of haploid and triploid celestial goldfish, presenting essential data derived from preliminary investigations. The research delved into three main areas: the short-term preservation of celestial goldfish gametes, the interaction between oocytes and foreign sperm, and the effects of temperature on fertilized eggs concerning hatching rates and late-stage ocular development. Initially, the study explored the optimal semen dilution ratio for celestial goldfish under microscopic examination. And the hybridization of the largemouth bass and celestial goldfish was investigated: largemouth bass sperm was crossbred with celestial goldfish eggs, and it was found that their sperm could not stimulate the development of celestial eye eggs. At last, celestial goldfish fertilized eggs were stimulated at 4 °C and −20 °C, respectively, to observe their impact on the hatching rate and later celestial eye rate. The results revealed no significant differences in hatching rate and celestial eye rate between the cold stimulus groups and the control group, but numerically, the 4 °C cold stimulation reduced the celestial eye rate of celestial goldfish fertilized eggs. The research provided fundamental data for artificial breeding and hybridization experiments in celestial goldfish.

Effectiveness of Items of Jarak Leaf Extract (Jatropha Curcas) with Different Dosages to Prevent Attacks of Fungs Saprolegnia sp on Gold Fish (Cyprinus carpio L) EGGS

The aim of the study was to determine the effect and optimal dose on hatchability, hatching time and prevalence. The study was carried out in two stages, namely the manufacture of jatropha leaf simplicia dried using an oven at 70 oC for 5 minutes. Puree using a blender. Weighed according to the treatment, namely A 3 g/L, B 5 g/L, C 7 g/L and D 0 g/L. The next stage is spawning the broodstock, and selecting 2,400 eggs that have been successfully fertilized, each treatment with 200 eggs. Each treatment was soaked for 4 minutes. The eggs were transferred to a hatching container with a volume of 5 L of water. The experiment was conducted using an experimental method (CRD), the factor tested was the effectiveness of castor leaf extract with different doses on hatching time, hatchability and prevalence. The results of observations of hatching times have a different number of hatchings. Treatment 3g/L 5 grains, treatment 5g/L 3 grains, without soaking 1 grain with hatching time 30 hours after fertilization. The most eggs hatched at 42-54 hours in the 3g/L treatment 479 eggs and the lowest in the treatment without soaking 258 eggs. For treatment 5g/L 419 grains and treatment 7g/L 380 grains. The effectiveness of giving effect, prevalence and presentation of hatching eggs in the 3g/L treatment has a success rate of 5%, for hatching time of 30-52 hours, prevalence is 20.17% and percentage of hatching eggs is 79.83%.

Effectiveness of papaya seed (Carica papaya L) solution against fungal prevalence and hatching power of koi carp (Cyprinus carpio L) eggs

One of the causes of the low production of koi carp seeds is fungal attack during the egg-hatching period, so natural treatments need to be carried out, including the use of papaya seeds. Papaya seeds contain antifungal compounds in the form of tannins, flavonoids, saponins, and alkaloids. The purpose of this study was to determine the effective dose of papaya seed solution in reducing the prevalence of the fungus and increasing the hatchability of koi goldfish eggs. This study was designed using a completely randomized design, which consisted of 5 treatments with 4 replications each. The treatment tested was papaya seed solution with treatment doses A=control, B=125 mg L-1, C=150 mg L-1, D=175 mgL-1, and E=200 mg L-1. Variables measured included the prevalence of the fungus, egg hatchability, observation of the fungus, hatching time, and water quality. The results showed that treatment with 125 mg L-1 of papaya seed solution reduced the prevalence of the fungus by 32.5% and resulted in the highest egg hatchability of 67.5%. The high hatchability of eggs is due to the presence of antifungal compounds in the form of flavonoids, saponins, tannins, and karpain contained in papaya seeds which provide protection for eggs against fungal infections so that eggs can hatch properly. The best dose of papaya seed solution to prevent fungal infection in koi carp eggs obtained at 200 mg L-1, 11.25%.

Incaptive culturing of Goldfish and Koi carp in Punjab, Pakistan

This study observed the captive culture of Carassius auratus and Cyprinus carpio in the Potohar region, Punjab, Pakistan. Captive culturing of both species was conducted up to one-month post hatchlings. The sample size was 180 (90 goldfish and 90 koi carp) and kept in cemented raceways under optimum conditions. The study period was from October 2019 to April 2020. The natural breeding season for Carassius auratus and Cyprinus carpio was from 25th January to 5th February and the end of February to 11th March, respectively. The induced breeding duration for goldfish and koi carp was from 6th to 25th February and for koi carp from 12th to 30th March, respectively. For artificial breeding, the synthetic hormone Ovaprim C was injected intra-peritoneally at 0.5 ml/kg and 0.1 ml/kg body weight of females and males, respectively. Both the species were fed a 30% crude protein diet. Hydrilla plants were used for the adhesion of eggs. The female to male ratio was 2:3. Approximately 4500 to 5000 eggs of goldfish and 17000 to 18000 eggs of koi carp were laid. Fertilization, hatching, and survival rates observed for both were approximately 74%, 57% and 42.5%, respectively.

Production of common carp donor-derived offspring from goldfish surrogate broodstock

Common carp (Cyprinus carpio) is the fourth most-produced species in worldwide aquaculture. Significant efforts are invested in breeding and preservation of genetic integrity of this important species. However, maintaining a carp gene bank in situ can be demanding due to the large body size of the fish. Moreover, ex situ gene banking in common carp is as in other fish species limited to sperm cryopreservation. Recent progress in reproductive biotechnology in fishes has allowed the transfer of germ stem cells (gamete precursors) between individuals or even species. After maturation, the recipients are producing gametes of the donor. Surrogacy can serve as a valuable tool in germplasm banking to recover cryopreserved germ stem cells. Some unfavourable characteristics of the donor species such as long maturation time or large body size hampering its reproduction can be overcome by choosing a surrogate with more convenient characteristics. Efficient protocols for cryopreservation of common carp male and female germ stem cells have been recently developed in our laboratory. The next step has been to assess the potential of smaller goldfish (Carassius auratus) surrogates to produce donor-derived gametes of common carp after intraperitoneal transplantation of testicular cells.High transplantation success was achieved when 44% of the surviving goldfish produced pure donor-derived gametes of common carp at the age of 3 years giving rise to viable progeny. Donor-derived identity of the offspring was confirmed by genotyping and the production of a typical phenotype corresponding to the donor species. Reproductive performance of chimeras was similar to goldfish controls. Assessment of gamete characteristics showed that the size of donor-derived eggs is between control common carp and goldfish eggs. Interestingly, flagellum length in donor-derived spermatozoa was comparable to the common carp flagellum and significantly shorter than goldfish flagellum. Genotyping of the Y chromosome locus in chimeric goldfish provided a novel insight on the fate of transplanted cells, where only genotypic females were capable of producing eggs, while both genotypic males and females were capable of producing sperm. The present technology can be combined with cryopreservation procedures to ease needs for common carp breeds preservation and their recovery using many times smaller goldfish surrogates but also serve as a convenient model to study interspecific surrogacy in cyprinids.

The effect of feed larvae Chironomus sp. and high pellet protein to seedling goldfish (Carassius auratus)

Goldfish production increase in four years, specifically 66,823,000 in 2010 to 72,997,000 in 2014. The increment of goldfish production growth altogether with problems which is a discontinuity of fry stock. The solution for this problem is the purpose of this study, which is understood techniques in Goldfish (Carassius auratus) hatchery. The feed given to goldfish brood is blood worms (Chironomus sp. larvae) and pellets with a ratio of 50:50 as much as 3% of the biomass. Goldfish hatchery techniques involve broodstock cultivation, spawning techniques, larval development observation, and larval cultivation. Two kinds of Goldfish used, namely Oranda and Mutiara Goldfish. The results of Oranda goldfish spawning and Mutiara goldfish spawning consecutively are Fecundity 875 eggs, FR 94%, HR 91.83%, SR 93.04% and Fecundity 3850 eggs, FR 93.66%, HR 92.48%, and SR 91.10%. Larval development observation includes embryogenesis until post-hatched larval. Larval cultivation consists of giving various types of feeds, which are artemia nauplii (for 3-7 days old larval), Moina (for 7-14 days old larval), and blood worm or tubifex (> 14 days old larval). Fertilized goldfish eggs will develop through several phases, including zygotes, initial cleavage, blastula, gastrula, segmentation, pharyngula, egg hatching, and development of larvae after hatching.

ERK Signaling Pathway Regulates Embryonic Survival and Eye Development in Goldfish, Carassius auratus

The extracellular signal-regulated kinase (ERK) is one of the three major types of mitogen-activated protein kinases. Previous studies showed that ERKs mediate various signaling pathways for cell proliferation, differentiation, survival and transformation in mammals. In the present study, we use goldfish as a model system and demonstrate that ERK kinases play important roles in promoting embryonic survival and regulate development of eye and trunk in vertebrates. ERKs are highly expressed in multiple tissues including lens epithelial cells, lens fiber cells, retina, brain, muscle and heart of adult goldfish. Injection of the dominant negative ERK mutant (DNM-ERK) into the fertilized eggs of goldfish significantly inhibited ERK activity at blastula stage, and completely blocked ERK activity at gastrula and later stages. As a result, the blastula cells were induced into apoptosis, and majority of the injected embryos were lethal at embryonic stages. At the molecular level, inhibition of ERK activity by DNM-ERKs suppressed phosphorylation of Bad at Ser-112 to promote apoptosis. Similar results were observed when MEK activity was inhibited by U0126 treatment. The survived embryos display significant abnormality in the phenotypes of both eye and trunk. Associated with the abnormality in the eye development, phosphorylation in Pax-6 and expression of HSF4 were significantly decreased and expression of the β-crystallin gene was also downregulated. These results provide novel information regarding the roles of ERKs in regulating vertebrate development.

Distribution and function of germ plasm in cytoplasmic fragments from centrifuged eggs of the goldfish,Carassius auratus

Summary In teleosts, primordial germ cells (PGC)s are formed by the inheritance of cytoplasmic determinants called ‘germ plasm’ during early embryonic development. Although several molecular components of the germ plasm have been identified, it is still unclear if cytoplasmic regions that show expression of germ cell specific marker genes such as vasa and nanos1 are necessary and sufficient for inducing PGCs in the embryo. In this study, the relationship between PGC formation and yolk granules was examined by reducing numbers of granules in the embryo shortly after fertilization. Ten minutes after fertilization, goldfish eggs were centrifuged at 700 g. This treatment resulted in the formation of a transparent blastodisc with apparently no yolk granules. When this segment was removed from the centrifuged egg and placed in culture, it exhibited a holoblastic mode of cleavage and developed into a spherical embryoid body. Maternal vasa mRNA was detected at the connections between blastomeres that developed from the separated fragment. Electron dense structures could be detected along the cleavage furrow in a position seemingly identical to vasa mRNA localization. When the spherical embryoid body from the centrifuged eggs was transplanted onto the blastodisc of a normal blastula stage embryo, PGCs from the donor embryo were detected around the genital ridge in the resulting chimeric larva at 10 days post-fertilization. These results suggest that cytoplasmic fragments from centrifuged eggs contain factors sufficient for PGC differentiation. However, transplantation of the putative cytoplasmic germ plasm into host blastodiscs did not result in the formation of PGCs.

Exploration of transgenic method for goldfish and loach with the piggyBac transposon

Development of transgenic fish techniques and application will promote traits improvement of fish and benefit exploration of its gene function.To investigate the applicability of the transposon piggyBac in Cyprinidae and Cobitidae fish,the expression element of DsRed under the control of PAβ promoter was inserted into the plasmid pigA3GFP to generate transgenic vector pigA3GFP-AβDsRed.The results of the CIK cell transfected with pigA3GFP-AβDsRed showed that the transposon piggyBac could transfer exogenous genes into CIK genome,and both of the promoter A3 from silkworm and the promoter CMV from CMV have the bioactivity.Moreover,the pigA3GFP-AβDsRed and pigA3GFP were mixed with helper plasmid helper-pigA3 respectively,and then were introduced into the eggs of goldfish and loach by sperm-mediated transfer.The results of fluorescence observation,PCR and Dot blotting verified that both transgenic goldfish and loach were obtained.Therefore,PB transposon was considered to be active in some fishes of Cyprinidae and Cobitidae.

The formation of improved tetraploid population of red crucian carp × common carp hybrids by androgenesis

Bisexual fertile diploid androgenetic individuals (A(0)) (2n=100) were formed by androgenesis. In this way, the diploid spermatozoa from male allotetraploid hybrids (AT) (4n=200) of red crucian carp (Carassius auratus red var.) (female) x common carp (Cyprinus carpio L.) (male) were used to fertilize the UV-treated haploid eggs of goldfish (Carassius auratus), and living androgenetic diploid fish were developed. The A(0) became sexually mature at the age of 2 years, and they fertilized with each other to form their offspring (A(1)). In this study, we observed the chromosomal number, gonadal structure and appearance of A(1) fish. The results are as follows: (1) In A(1), there were 85% tetraploids (A(1)-4n), 10% triploids (A(1)-3n) and 5% diploids (A(1)-2n), suggesting that diploid A(0) could produce diploid gametes. It was concluded that the formation of diploid gametes generated from diploid A(0) was probably related to the mechanism of pre-meiotic endoreduplication. (2) Among A(1), only A(1)-4n possessed normal ovaries and testes. The mature males of A1-4n produced white semen. Under the electron microscope, the head of diploid sperm generated by A(1)-4n was bigger than that of haploid sperm generated by red crucian carp. In the testes of the A(1)-4n, there were many mature normal spermatozoa with a head bearing plasma membrane and a tail having the typical structure of "9+2" microtubules. Between the head and the tail, there were some mitochondria. The ovaries of A(1)-4n developed well and mainly contained II, III and IV-stage oocytes. The IV-stage oocytes were surrounded by inner and outer follicular cells. The micropyle was observed on the oolemma of follicular cells. There were abundant yolks and plenty of endoplasmic reticulum in the cytoplasm of IV-stage oocytes. Because A(1)-2n and A(1)-3n were distant crossing diploid hybrids and triploid hybrids respectively, they possessed abnormal gonads, and no mature semen and eggs were observed. (3) Compared with allotetraploids, the A(1)-4n fish not only had advantages such as fast growth rate and strong resistibility but also showed some new good performances such as high ratio of body width to body length, smaller heads and shorter tails. These results indicated that androgenesis could produce bisexual fertile tetraploids and improve the shape of allotetraploid hybrids as well, which will be of great significance in both the cell genetics research and fish breeding.

Induced interspecific androgenesis using diploid sperm from allotetraploid hybrids of common carp×red crucian carp

In the present study, viable diploid androgenetic individuals (AT-ag) (2 n = 100) have been developed in UV-radiated eggs of goldfish (GF) ( Carassius auratus) following fertilization with diploid spermatozoa from male allotetraploid hybrid (AT) F 13 (4 n = 200) of red crucian carp ( C. auratus red var.) (♀) × common carp ( Cyprinus carpio L.) (♂). In the experimental groups, eggs were inactivated by UV-rays, the range of UV-radiation dose tested varied from 240 to 600 mJ/cm 2, the relative high hatching rate (4.1 ± 0.4%) and survival from hatching to start of feeding (41.3 ± 2.6%) were given at UV dose of 300 mJ/cm 2. The androgenetic nature was confirmed by chromosome observation and DNA content measurement of somatic cells by a flow cytometer. The AT-ag were diploid (2 n = 100) whereas the controls (GF × AT) were triploids (3 n = 150). The diploid AT-ag grew slower than the triploid GF × AT. The AT-ag and GF × AT were also morphologically distinguishable. The AT-ag began to sexually mature at the age of 2 years, and their fertility further increased at the age of 3 years. The tetraploids were obtained in the offspring (F 1ag × ag ) produced by mating the males with females of AT-ag and in the progeny (AT-ag × AT) generated by crossing the males of AT with the females of AT-ag, indicating that diploid AT-ag could produce diploid gametes. All the sex ratios of males to females in AT-ag, F 1ag × ag , AT-ag × AT were not significant ( P > 0.05) from the ratio of 1:1, suggesting the XXXY sex-determining mechanism in the males of AT. The present study indicated that bisexual fertile diploid AT-ag were successfully induced from diploid spermatozoa of AT.

Cytoplasmic impact on cross-genus cloned fish derived from transgenic common carp (Cyprinus carpio) nuclei and goldfish (Carassius auratus) enucleated eggs.

In previous studies of nuclear transplantation, most cloned animals were obtained by intraspecies nuclear transfer and are phenotypically identical to their nuclear donors; furthermore, there was no further report on successful fish cloning since the report of cloned zebrafish. Here we report the production of seven cross-genus cloned fish by transferring nuclei from transgenic common carp into enucleated eggs of goldfish. Nuclear genomes of the cloned fish were exclusively derived from the nuclear donor species, common carp, whereas the mitochondrial DNA from the donor carp gradually disappeared during the development of nuclear transfer (NT) embryos. The somite development process and somite number of nuclear transplants were consistent with the recipient species, goldfish, rather than the nuclear donor species, common carp. This resulted in a long-lasting effect on the vertebral numbers of the cloned fish, which belonged to the range of goldfish. These demonstrate that fish egg cytoplasm not only can support the development driven by transplanted nuclei from a distantly related species at the genus scale but also can modulate development of the nuclear transplants.

Nucleocytoplasmic incompatibility in androgenetic fish hybrids can be overcome

Many androgenetic fish hybrids are nonviable due to the disturbed interaction between the foreign nucleus and the cytoplasm. It has been proposed that this incompatibility can be overcome if eggs from interspecific hybrids and sperm from one of the parental species are used for diploid androgenesis. Indeed, the androgenetic progeny obtained as a result of the insemination of the enucleated eggs of goldfish and carp hybrids by the carp spermatozoa proved to be viable and fertile. This approach may be used for reconstitution of the genotypes of rare or disappearing fish species with the help of induced androgenesis, if their native or cryoconserved sperm is available.

Storage of unfertilized eggs of rainbow trout ( Oncorhynchus mykiss) in artificial media

Unfertilized eggs of rainbow trout ( Oncorhynchus mykiss) were stored in coelomic fluid and in Cortland medium (devoid of bicarbonate and phosphate), which was buffered with 20 mM Hepes (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) or Tris–HCl (Tris hydroxymethyl aminomethane hydrochloride) and adjusted to a pH of 8.5. Eggs stored in these solutions for 24 and 48 h, were fertilized using sperm derived from 4–6 males. The sperm was applied in a dilutant (127 mM NaCl, 20 mM Tris–HCl, pH 9.5). The percentage of embryos reaching the eyed and hatching stages was recorded as an index of fertility. Unfertilized trout eggs stored for 48 h at 12–13°C in Cortland medium buffered with Hepes or Tris exhibited the same fertility as eggs fertilized prior to storage. In fact, the percentage of embryos reaching the eyed stage was significantly greater in eggs stored in the modified Cortland solutions than in eggs stored for the same amount of time in coelomic fluid. It appears that fertility may be better in eggs stored in Cortland medium containing Hepes than in medium containing Tris. Since serine protease inhibitors have been shown to enhance fertility of goldfish eggs, the effect of a soybean trypsin inhibitor on egg fertility was investigated. Trout eggs stored for 24 h in Cortland medium containing 2.0 mg soybean trypsin inhibitor/ml were almost completely infertile. Eggs stored in modified Cortland medium and fertilized in the direct presence of soybean trypsin inhibitor (0.01 mg/ml sperm dilutant) exhibited the same percentage of eyed and hatched embryos as eggs stored in Cortland medium alone. This suggests that the inhibitor did not directly block fertilization but had an effect during storage. The results indicate that modified Cortland medium can be used for the storage of trout eggs for at least 2 days. Furthermore, washing and storage for a short time in this medium may actually enhance the fertilization of the eggs of some females.

Localization of a putative epiboly-determining factor in oocytes of the goldfish (Carassius auratus)

It is unknown whether cytoplasmic determinants in goldfish eggs are asymetrically localized before maturation. In this study fully grown goldfish oocytes with intact germinal vesiles (GVs) were ligated with baby hair loops along desired planes into two parts, matured in vitro, and inseminated. Embryos developed from the animal halves with GV of oocytes ligated along the equator were unable to undergo epiboly, while those developed from the GV-containing parts of oocytes ligated along the animal-vegetal axis were able to. Also, embryos developed from the animal halves obtained from fertilized eggs could undergo epiboly. From these results, it was postulated that the goldfish's premature oocyte possessed a putative factor in the vegetal hemisphere which was responsible for epiboly of the embryonic cells.

Overripening of ovulated eggs in goldfish: I. Morphological changes

Goldfish eggs retained in the ovarian cavity become overripe within 24 h after ovulation. Three stages of an overripening process could be identified. The overripe egg is characterized by increased translucency, movement of cytoplasm with cortical alveoli and unfused oil droplets to the animal pole, partial breakdown of the cortical alveoli, and finally the intermingling of these cell components with yolk granules in later stages. It is also larger than the newly ovulated egg and its chorion is thinner with surface modifications involving the recessing or disappearance of the pore plugs.

Inhibition of Chorion Expansion and Preservation of Fertility in Goldfish (Carassius auratus) Eggs by Protease Inhibitors

The in vitro effects of protease inhibitors on chorion expansion and the fertility of goldfish (Carassius auratus) eggs were investigated. Expansion of the chorion in ovulated eggs was blocked by the serine protease inhibitors benzamidine and soybean trypsin inhibitor when they were held in a goldfish Ringer solution. Eggs in which chorion expansion was inhibited retained their fertility for 30 min when held in this solution. In contrast, ovulated eggs lost their fertility in freshwater even in the presence of a protease inhibitor. The results suggest that chorion expansion and loss of fertility in water-activated goldfish eggs may involve proteolysis which was blocked by benzamidine and soybean trypsin inhibitor. Moreover, the blockage of chorion expansion may be pivotal to the preservation of fertility in eggs held in Ringer's solution with soybean trypsin inhibitor. The development of this solution provides a means to temporarily hold ovulated goldfish eggs in a viable state outside the female and will permit further studies on fertilization in this species.

Transfer of the gene for neomycin resistance into goldfish, Carassius auratus

A recombinant DNA construct containing the neo gene controlled by a promoter from the Rous sarcoma virus (RSV) was microinjected into newly fertilized, dechorionated goldfish ( Carassius auratus) eggs. The neo gene confers resistance to the neomycin analog drug G-418. Results of Southern blot analyses were consistent with incorporation of single or multiple copies of the gene into the genomic DNA of one examined fish. Evidence of neo mRNA in RNA dot-blot analysis indicated that the RSV promoter had initiated transcription within a piscine genome. The utility of the neo gene as a selectable marker for transgenic fish was evaluated by G-418 selection on newly hatched and juvenile fish but proved inconclusive. Reasons for the discrepancy between neo expression and G-418 selection results are discussed.

The reaction time of organ-forming substance in goldfish EGG and its relationship with mesodermal formation

Fertilized goldfish eggs were dechorionated with a pair of forceps and were cut off along or a little above the equator into animal and vegetative parts at desired stages with a glass needle or ligated into two connected fragments before cleavage with baby hair loop. Some of the ligated eggs were detached by further fastening soon after ligation, and some released later at different stages (2-cell, 16-cell, 128-cell, 512-cell, mid-blastula) to let the organ-forming substance (OFS) enter the blastoderm. The cholinesterase (ChE) in the resulting embryos was assayed. The results are as follows. 1. All the 142 embryos developed from the animal hemispheres cut off or ligated off before cleavage gave rise to hyperblastula in which no ChE activity was observed. 2. All 50 embryos obtained from animal halves isolated at the 8-cell stage produced ChE. 3. Embryos developed from the eggs released before the 512-cell stage formed ChE, but the later the releasing of the hair knots, the smaller the number of ChE-producing embryos. 4. After the 512-cell stage (excluding this stage), neither ChE nor tissue differentiation occurred in the embryos developed from the unfastened eggs though their OFS flow was set free. Since ChE is thought to be a muscle-specific enzyme in the early developmental stage, it is concluded that the OFS in goldfish egg appears to be indispensable for the establishment of the mesoderm.

Enzymatic Dechorionation of Goldfish, Walleye, and Northern Pike Eggs

Removal ofthe chorion from fish eggs facilitates observation ofpiscine embryogenesis and allows efficient microinjection during gene transfer protocols. Several treatments were screened to evaluate their effectiveness in removing the chorion from newly fertilized eggs of goldfish Carassius auratus, walleye Stizostedion vitreum, and northern pike Esox lucius without destroying egg viability. Goldfish eggs dechorionated in 2.5 mg/mL trypsin showed excellent viability. No effective procedure for dechorionation of walleye eggs was found. Northern pike eggs could be dechorionated in 0.6 mg/mL protease type XXV, but mortalities above 50% were commonly observed.