Artificial propagation and embryonic growth in Stinging catfish, Heteropneustes fossilis (Bloch, 1794) using S-GnRHa (salmon gonadotropin releasing hormone analogue)

An experiment was performed to observe the potentiality of synthetic hormone analogue in artificial propagation i.e., the embryonic and larval development of Heteropneustes fossilis. Broodfish were injected with S-GnRHa according to the following concentration: 1, 2.5 and 5 ml kg-1 of body weight (BW) to females and 0.5, 1.125 and 2.5 ml kg-1 BW to males, in treatment groups T1, T2 and T3, respectively each with three replicates. The fishes were ovulated at about 10-11 hours after the hormone injection. Result showed the highest fertilization (83.11±1.36) and hatching rate (89.56±1.04) in T2, whereas ovulation rate was 100% in all treatment groups. First cleavage was observed in 30 minutes of post-fertilization. Embryonic developmental period sequentially for 2-cell, 4-cell, 8-cell, 16-cell, 32-cell, 64-cell, Morula, Blastula, Gastrula, somatic formation, yolk-plug, twisting movement and pre-hatching were 00:30, 00:45, 01:10, 01:30, 02:00, 02:30, 03:00, 04:00, 06:40, 09:00-18:00, 19:00, 20:00-21:00 and 22:00 hours, respectively. Hatching occurred after 23:00 hours of fertilization. Finally, the current result suggested that S-GnRHa might be an effective synthetic hormone in artificial propagation of H. fossilis.

Artificial propagation and larval breeding tests of the african sharptooth catfish, Clarias gariepinus conducted in captive conditions

The African catfish Clarias gariepinus is the second most cultured species in many African countries, including Senegal. Despite its economic importance in local aquaculture, artificial propagation of the species that would allow obtaining quality seed throughout the year has not yet been mastered adequately. This study aimed at producing C. gariepinus quality and mass supply seed to enhance local production. Three different types of incubation (Macdonald's bottle, water lettuce and wire mesh frame) were tested to identify the most efficient and accessible method for the producers at low cost and with a high hatching rate. The hatching rates obtained for the three different incubation methods were 26.9%, 10.0% and 6.3% for the Macdonald bottle (MB), wire frame (WF) and water lettuce (WL), respectively, while the corresponding survival rates were 91.6%, 70.4% and 77.8%.77.8%. The high hatching rate obtained with the MB could be due to the influence of permanent water circulation, which is absent in the other two hatching systems. The survival rates decreased 15 days after hatching and were 3.24%, 2.04% and 7.16%, respectively. The survival rates obtained three days after hatching were satisfactory, but the significant decrease at 15 days after hatching especially during the post- weaning phase seems to be due to the food quality, and unrelated to the hatching system. The daily individual growth, weight gain and body size of the larvae was significantly higher for larvae fed with natural food compared those that received artificial food. These results indicate that larvae preferred and fed the natural food which was permanently available in the rearing tanks. The artificial food deposited on the bottom of the tank changes appearance over time and may not be appreciated and efficiently consumed by the larvae, which may negatively impact their growth performance.

Estimation of the Fecundity of Threatened Pethia ticto

In order to estimate fecundity of threatened small indigenous fish species, tit punti (Pethia ticto), an investigation was done at the Field Laboratory Complex, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh during June to August, 2017. The mean total lengths were 5.39 ±0.58, 5.20 ± 0.43, 5.79 ± 0.97 cm and mean ovary weights were 0.45 ± 0.20, 0.38 ± 0.15, 0.53 ± 0.26 g for the month of June, July and August, respectively. The fecundity of P. ticto for the month of June was estimated to be 1120-13892 with a mean of 5319.62 ± 3169.16, for the month of July it was 1071-12325 with a mean of 5407.68 ± 3186.82 and for the month of August it was 2268-14328 with a mean of 5919.92 ± 3436.29. The gonadosomatic index (GSI) were 16.62 ± 3.35, 19.01± 4.55 and 14.75± 2.53 for the month of June, July and August, respectively. The highest GSI was observed in July (25.77) and the lowest was 10.53 in June. Information of fecundity and GSI of P. ticto will be helpful for artificial propagation, conservation, and management of this fish species.

Carp seed transportation and distribution.

Carp seed trading has become an important enterprise to make money for hatchery/nursery owners and seed traders, engaging more than 100,000 people in Bangladesh. Aquaculture, in particular carp production, has increased dramatically with the introduction of artificial propagation. The bottleneck of artificial propagation has been removed with successful induced breeding. Induced breeding has been introduced into Bangladesh in the 1980s and since then carp seed production and trading have increasingly become the driving force for the dramatic expansion of aquaculture. Private hatcheries/nurseries have been dominating by producing about 97% of the total seed production. As a result, carp seed trading has become an important entrepreneurship.

Artificial propagation of grass carp (Ctenopharyngodon Idellus).

Grass carp (Ctenopharyngodon idella) has become the main aquaculture species in freshwater areas in Vietnam. This study reviews grass carp biology, growth, habitat, mature age/spawning season, seed, culture, diseases, breeding trechniques, fry rearing and nursery trechniques, and hatcheries in Vietnam.

Inference of ploidy by leveraging read depth from amplicon sequencing

Variation in ploidy occurs naturally in select plant and animal species. Ploidy variation can also occur spontaneously or be induced during artificial propagation of fish and shellfish. Studying species and systems that have variable ploidy requires techniques to infer ploidy of individuals. Massively parallel sequencing of biallelic SNPs has been used to infer ploidy, but existing techniques have several drawbacks. These include being limited to only comparing a fixed number of ploidies (diploidy, triploidy, and tetraploidy) and requiring that heterozygous genotypes in an individual be identified prior to ploidy inference. We describe a method of inferring ploidy from sequencing of biallelic SNPs based on beta-binomial mixture models. This method is generalized to apply to any ploidy and does not require prior identification of heterozygous genotypes. We demonstrate efficacy of this method for comparing ancestral octoploidy, decaploidy, and dodecaploidy (tetraploidy, pentaploidy, and hexaploidy for the sequenced SNPs) in white sturgeon and diploidy and triploidy in Chinook salmon with amplicon sequencing (GT-seq) data. Results indicated that ploidy could be reliably estimated for individuals based on distinct distribution of log-likelihood ratios (LLR) for known ploidy samples of both species that were tested. Confidence in ploidy estimates increased with sequencing depth. We encourage users to explore the sequencing depths and LLR critical values that provide reliable estimates of ploidy for a given organism and set of SNPs. We expect that the R package provided will empower studies of genetic variation and inheritance in organisms that vary in ploidy naturally or as a result of artificial propagation practices.