The use of S-GnRHa (salmon gonadotropin releasing hormone analogue) in induced breeding and early embryonic development of Gulsha, Mystus cavasius

Abstract

The current study was carried out to optimize the dose of the synthetic hormone for induction, and to observe the embryonic and larval developmental in Gulsha, Mystus cavasius. Induced breeding was conducted by using Ovupin (S-GnRHa) hormone (each 1.5 ml vial contain 0.2 mg of an analogue of S-GnRHa) at four different doses i.e., 0.25, 0.5, 1.0-and 1.50-ml kg -1 body weight (BW) for females, and the half of these doses were applied to males. Among the applied doses, 0.5 ml kg -1 BW for female and 0.25 ml kg -1 BW for male provided the maximum fertilization (83.66%) and hatching (80.0%) rates. The eggs of M. cavasius were strongly adhesive, with covering on egg surface. The average diameter of fertilized eggs just after spawning was 85.58±5.87 µm. After fertilization, the first, second, and third cleavage stages occurred within 20-25, 35-40 and 60-65 min, respectively. The identity of blastomeres was gradually lost and appeared at 64-cell stage to 128-cell stage onwards. The 64-cell stage appeared at 150-160 min and the morula stage 3:00-3:20 h (blastomeres completely lost), respectively. The gastrula stage appeared at 5:0-5:30 h in which the blastoderm spread in both the sides covering about 60-70% area, together with a thread-like germinal ring. Afterward, twisting locomotion was recorded at 23:30 h. The larvae started hatching at 24:00 to 25:00 h. The barbells were partially visible when the larvae were 10-12 h of age. Finally, the yolk sac was fully absorbed in the end of Day 3.

Observation of Water Quality Parameters on Induced Breeding of Bagrid Catfish in Bangladesh

“…The study denoted that 29-34oC temperature was identified as the optimum range for induced breeding. Ali et al (2021) reported that the maximum fertilization rate was 83.66% and the hatching rate was 80.0 percent, which is mostly similar to this experiment where the fertilization rate was 80% and the hatching rate was recorded at…”

Brood Rearing and Dose Optimisation for Induced Breeding of Raikor, Cirrhinus reba (Hamilton, 1822)

“…Reba's fertilized eggs (Figure 4b) demonstrate meroblastic cleavage within 30-35 min after fertilization (Figure 4c). By administering Gn-RH in Mystus cavasius, Ali et al (2021) observed the first cleavage to a 32-cell formation in 00:35-2:20h, whereas the new research ascertained the first cleavage achieved a 32-cell formation in 00:30-3:20h. At 190-210 minutes after fertilization, the morula phase was acquired (Figure 4c).…”

“…fertilization in M. cavasius. The C-shaped gastrula part (Figure 4e) starts at 6:0-6:40h post-fertilization, whereas Ali et al (2021) recorded it at 5:0-5:30h after fertilization. The winding motion of the embryo was seen in current research as it unwinds from being encircled over the yolk realm.…”

“…The small larvae were easily recognized by their distinct heads, trunks, and rear regions (Figure 3k). Hatching time in M. cavasius was 24-25h (Ali et al, 2021); in Rita rita hatching was started after 22h of incubation and completed after 30h of incubation at 35°C (Mollah et al, 2011); and in the C. batrachus hatching time varied between 23-26 hours at a temperature range of 31-37.5°C (Das, 2002).…”