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Monthly Variations in the Egg Size, Hatching Rate, Inclubation Time and Ovulation of Clarias Gariepinus

G.U. AHMED
Department of Fisheries Biology and Limnology, Bangladesh Agricultural University, Mymensingh

Abstract/ Executive Summary:

Induced spawing of African magur was carried out for a period of 7 months from March to September. Both the HCG(2 i.u./g b.w.) and PG (2PG/1000g fish) were used together for spawning. An increased percentage of eggs were released in July and hatching percentage was recorded in August, whereas, incubation period was the lowest (15 hrs.) in June.,The fertilized eggs were demersal and adhesive and. were 0.7, to 1.5 mm in diameter. The colour of eggs were greenish to grayish or grayish brown.

Keywords: African catfish, Induced spawning, Egg percentage

Location: Department of Fisheries Biology and Limnology, Bangladesh Agricultural University, Mymensingh

Start Date:

End Date:

Program Area: Animal Health and Management

Commodity: Cat fish

Objectives:

To investigate the procedure to local circumstances so far as the time of spawning and ovulation of fish.

Methodology:

The experiment was designed to carry out for a duration of 7 month from March to September. The brood stock of catfish were reared in ponds near Fisheries Faculty Building of Bangladesh Agricultural University, Mymensingh. Three pairs of catfish (mature male and female) were selected for induced spawning during each of the sampling period and sampling was carried out at an interval of 15 days. Both human chorionic gonadotropin (HCG) and pituitary gland (PG) was given at a dose of 2 i.u./g b.w. and 2 PG (4mg each)/ 1000g fish. The hormones were injected twice (half dose at each time) at an interval of 6 hrs. and ovulation was achieved after 5-7 hrs. of the second injection. The male catfish was dissected to collect testis and the females were stripped and eggs were collected over a small tray (36cm x 29cm x 6 cm). The testis was pressed and the milt obtained were spread quickly over the eggs. Eggs and milt were mixed properly by means of a feather and small amount of distilled water was poured over the eggs in order to confirm fertilization of eggs with sperms. The fertilized eggs were washed 3-4 times and spread homogeneously over hatching trays which were provided with continuous aeration and water circulation. When the eggs were hatched out, they were carefully separated from the dead eggs. By counting the number of hatched out eggs and dead eggs, the percentage of hatching was calculated. Other parameters like weight of eggs at ovulation, their sizes, colour and incubation period were also recorded fortnightly. Water qualtiy parameters such as temperature, dissolved oxygen and pH were also recorded at an interval of 7 days.

Source of Information: BAU Res. Prog. 7: 717-724; 1993

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

An increased percentage of eggs were released in July and hatching percentage was recorded in August, whereas, incubation period was the lowest (15 hrs.) in June. The fertilized eggs were demersal and adhesive and. were 0.7 to 1.5 mm in diameter. The colour of eggs were greenish to grayish or grayish brown.

Knowledge Management: Report/Proceedings