2.1. Study site: This study was conducted in the pond complex of the campus of Bangladesh Fisheries Research Institute (BFRI), Floodplain Sub-station (FPSS), Santahar, Bogra, Bangladesh during 2012-2013.
2.2. Collection of Cuchia brood fish Females averaging 280g and males averaging 190g were collected from the Raktadaha Beel of Santahar, Bogra and Chalan Beel of Pabna, Bangladesh.
2.3. Pond preparation A pond having an area of five (5) decimal was prepared by sun drying followed by liming at the rate of 1 Kg/Decimal. After drying up the pond, Urea, TSP and cow-dung were applied at the rate of 0.100, 0.075 and 8 Kg/Decimal, respectively. After Cuchia stocking, fertilizers were used fortnightly depending on the primary production of the pond. Water depth was maintained at about 1-1.25m. The pond was protected by fencing with nylon net, bamboo, and rope. Fencing was done to stop entering of different fish-eating animals like snake, otter, and other reptiles. Water hyacinth, Helencha (Enhydra fluctuans) and PVC pipes were provided to create suitable and safe shelter.
2.4. Rearing of brood Cuchia in prepared pond Cuchia broods were reared in a prepared pond of BFRI, Floodplain Sub-Station for three months from January to March 2013. Live foods like earthworms, moribund fingerling fish were provided at the rate of 3% body weight twice daily. Guchi (Mastaecmbelus puncalus), Carpio (Cyprinus carpio), Taki (Channa punctatus) and Puia (Lepidocephalus guntea) were released in the pond for natural breeding because cuchia will take those breeding-after larvae as food. 2.5. Experimental steps The experiment was conducted into Induced breeding technique. In this experiment, various doses of cPGE, HCG, Cuchia PG, Ovaprim and Pregnyl considered as three steps: 1.Cistern, 2. Hapa and 3. Pond. 2.6. Maturity stages indication Identification of male & female is very difficult but some external characteristics and GSI mean to ensure the differentiation of male & female. The mean gonad somatic index of the female was minimum (2.78) in the month of December and January and the mean gonad somatic index of the female was maximum (5.00) in the spawning stage of maturation with one pick in April to June. The variation of mean GSI occurred in mature fishes and the peak would be indicative of the peak period of spawning. Sexual maturity of broods was confirmed by observing the body color and shape of the genital organ.
Broods were collected from rearing pond. A total fifty-two (26 Male & 26 Female) were selected for induced breeding. Collected female & male brood’s weights were average 335g and 245g respectively. Female and male broods were kept for a few hours in separate cisterns for conditioning. Before induced breeding broods were taken out from the cistern and caught with a wet soft cloth. When female were injected twice while male received a single dose. In case of the female, the time interval between two injections was maintained at 6-12 hours. The male was given a single dose at the time of second dose of the female. After that, the injected broods were transferred to the Cistern, Hapa and Pond. Two pairs of injected M. cuchia were stocked at a ratio of 1:1 in each Cistern, Hapa and in Pond.
2.8. Water quality measurement Physicochemical water quality parameters were measured weekly. A centigrade thermometer measured the temperature of air & water. HACH water test kit (Model-FF-2, USA) was used to measure pH, dissolved oxygen (DO) and alkalinity. Water quality of Cistern, Hapa and Pond was measured regularly following standard methods.