Induced Breeding Practices of the Freshwater Fish Hatcheries in Bangladesh

Study Area and Duration

The study was conducted with fish hatcheries of northern region of Bangladesh (Figure 1). The Bangladesh consists of 08 divisions. Padma, Meghna, Jamuna, Brahmaputra and Karnafuly rivers are the rivers of the eight divisions. The study areas (eight divisions) are shown in the location map.

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Sampling of Fish

The investigation was conducted from 2019-20 and was sampled simultaneously for breeding season of Indian major carps, exotic species and indigenous species from January to September to get a true picture of breeding season, breeding period, ovulation and hatching status of ovulated fishes.

Analysis of Experimental Data

The collected data were cheeked and cross-checked for reliability and accuracy. The data were analyzed through one way ANOVA using MSTAT followed by Duncan’s Multiple Range Test to find out whether any significant difference existed among the different means [10].

Brood Fishes Selection for Induced Breeding

Indian major carps (Labeo rohita, Catla catla and Cirrhinus cirrhosus), three exotic carps (Hypopthalmicthys molitrix, Ctenopharyngodon idella and Cyprinus carpio) and Thai Pangus (Pangasius sutchi) were the dominant fish species used as brood fish in most hatcheries of Bangladesh [11]. Genetically improved and healthy brood fish selection is important for induced spawning of Indian major carps [5].

Inducing Agents and Hormonal Dose Selection

In the studied area, Hatchery owners used three types of inducing agents such as pituitary gland (PG), human chorionic Gonadotropin (HCG) and Gonadotropin Releasing Hormone analogues (GnRHa) under the trade name Ovupin, ovafish, ovaprim, ovacline, ovamach, pragnil, ovatid (100 mg Domperidone + 0.2 mg S-GnRHa), etc. for induced breeding purposes. Pituitary gland (PG) extract and Human Chorionic Gonadotropic (HCG) hormone were commonly used inducing agents for induced breeding though some other agents like Ovaprim, Profasi, Pregnyl, Luteinizing hormone releasing hormone (LH-RH) etc. were also used for both indigenous and exotic fish species (Figure 2). Though PG extract/ HCG injection of female fish is always given with one or two doses; in case of two doses six hours interval was maintained between two injections but the males were injected with a single dose of PG or HCG at the time of the first injection of the females with a continuous flow of fresh water. The dosage varies with the species, temperature, potency of the pituitary gland, gonadal maturity of the recipient and the prevailing climatic conditions [12].

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Incubation and Hatching

The present practices of using dose of Human Chorionic

Gonadotropin (HCG) and Gonadotropin Releasing Hormone Analogues (GnRHa) mentioned below (Table 1).

The present practices of using dose of Pituitary gland (PG) (mg/kg) mentioned below (Tables 2 & 3).

Ahmed [13] stated that PG influenced the spawning of Labeo rohita. Atz and Pickford [14] and Chaudhuri [15] mentioned various aspects of the fish pituitary gland and its role in modern aquaculture (Figure 3). From the investigational period, it was observed that the fish ovulated

98% when the appropriate doses of hormonal injections were applied and maintained temperature range (22-28)0C Alikunhi, et al. [16], Alam and Bhuiyan [17], Bhuiyan and Aktar [6], Haque [18] and Mahanta et al. [19]).

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Incubation and Hatching

During the survey, it was found that the ovulation rate of Rui (Labeo rohita), Catla (Catla catla), Mrigel (Cirrhinus cirrhosus), Calibaush (Labeo calbasu), Bata (Labeo bata), Gonia (Labeo gonius), Silver Carp (Hypopthalmicthys molitrix), Bighead Carp (Hypopthalmicthys molitrix), Grass Carp (Ctenopharyngodon idella), Common Carp (Cyprinus carpio), Black Carp (Mylopharyngodon piceum), Thai Puti or Raj Puti (Barbonymus gonionotus) and Thai Pangus (Pangasius sutchi) fish species were 65, 70, 74, 80, 84, 88, 92, 96, 98, 90 and 88%, respectively (Figure 4). The regression type is Polynomial and the equation is y = -0.751x2 + 11.36x +49.705 (R2 = 0.8449).

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The fish hatching rate were recorded at the rate of 52, 55, 62, 71, 77, 80, 86, 90, 94, 80 and 62%, respectively in different hatcheries (Figure 4). The regression type is Polynomial and the equation is y = -1.1254x2 + 15.96x +29.182 (R2 = 0.8328). Highest ovulation and hatching was recorded at 99% and 94% in the month of June Singh BN, et al. [20] in the different hatcheries. The ovulation rate of Pabda (Ompok pabda), Gulsa (Mystus cavasius), Mrigel (Cirrhinus cirrhosus), Calibaush (Labeo calbasu), Bata (Labeo bata), Gonia (Labeo gonius), Tengra (Mystus tengra), Koi (Anabas testudineus), Shing (Heteronopneustes fossilis) and Magur (Clarius batrachus) fish species were 70, 76, 81,

84, 86, 88, 97, 98, 99, 90, 84 and 70%, respectively (Figure 5). The regression type is Polynomial and the equation is y = -1.0082x2 + 12.96x + 53.97 (R2 = 0.8749). The fish hatching rate were recorded at the rate of 58, 61, 72, 76, 82, 91, 93, 94, 73, 68 and 6%%, respectively in different hatcheries (Figure

5). The regression type is Polynomial and the equation is y = -1.289x2 + 16.269x +36.958 (R2 = 0.849). Highest ovulation and hatching was recorded at 99% and 94% in the month of July (Singh BN, et al. [20] in the different hatcheries.

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From this study on the survey of the fish hatcheries of Bangladesh, it was found that fish hatcheries contributed to a remarkable production of inland fish species as well as to the aquaculture development of Bangladesh. In the fisheries sector, induced breeding has opened the door of a new horizon throughout the country. Quality and quantity seed of fish production is important for aquaculture sector to give logistic support of farmer. It is also necessary to develop hatchery facilities which include induced breeding techniques for the development of aquaculture in Bangladesh.