Breeding biology and dose optimization for captive breeding of striped dwarf catfish Mystus vittatus using different hormones

The striped dwarf catfish, Mystus vittatus, a small indigenous fish of Bangladesh is scarce facing anthropogenic interventions. The present study depicts the captive breeding of M. vittatus applying different stimulating hormones which might improve the production. For this purpose, 400 wild brood fish of M. vittatus were collected and some breeding parameters such as gonado-somatic index (GSI), hepato-somatic index (HSI) and fecundity were measured at 15 days interval at each month during a year. For captive breeding, the broods were kept in the containers dividing into two different groups (male: female sex ratio 1:1 and 1:2) treated with carp pituitary gland (CPG: 4 to 12 mg/kg), flash (S-GnRHa: 0.4 to 1.2 mL/kg) and CPG plus flash hormones (2+0.2 to 6+0.6 mg-mL/kg) by 15 different doses and planned with a single dose for male and female. A control unit with no hormone was designed for each sex ratio. For evaluating the breeding performance, fertilization rate, hatching rate and survival rate of larvae were compared. In addition, the water quality parameters (temperature, DO, TDS, and pH) of incubators were checked. Maximum GSI value (25.54±5.86%) was found in mid-July and minimum (0.11±0.01%) was in mid-October, whereas the HSI value was lowest in mid-July for both female (1.61±0.11%) and male (2.40±0.08%). The average fecundity was 16175±10803 from end-March to end-September whereas the highest and lowest values were 32794±1284 in mid-July and 2109±412 in mid-September. Based on the GSI and HSI values of male and female, mid-July is the spawning season of this species. The higher latency period (8-9 hrs.) was noted with CPG and lower (6-7 hrs.) with the CPG plus flash hormone. The highest fertilization rate (92.6±6.38%), hatching rate (78.4±5.73%) and survival rate (69±7.03%) were found with a dose of 3+0.3 mg+mL/kg (CD2) of fish at the sex ratio of 1:2 whereas the average water parameter of temperature, DO, pH and TDS were 29.72±0.30^ºC, 8.61±0.08 mg/L, 7.46±0.01, 180.49±18.53 mg/L. In captive conditions, the seed of M. vittatus can be mass-produced and helpful to aquaculture and conservation through this research.