Gonadal Development and Maturity Pattern of Long Whiskered Catfish (Spereta aor)

Abstract

Month wise gonadal development and maturity pattern of long whiskered catfish (Spereta aor) were examined over the year. Gonadal developments were examined by macroscopically and microscopically and histological observations were assessed to establish the oocyte development of ovary. Macroscopically four stages of oocyte development were identified and which is further demonstrated by histological study. The ovaries of S. aor were paired, more or less elongated. The color of ovary varied from reddish-brown to light yellowish during breeding season of S. aor. The GSI values were gradually rising in the month of July to August. The highest gonado-somatic index (GSI) of female S. aor was 2.82±0.02 in August. On the other hand, the lowest gonado-somatic index of female S. aor was 0.63±0.03 in January. The highest hepato-somatic index (HSI) of S. aor was 2.24±0.06 in January. The lowest hepato-somatic index (HSI) of female S. aor was 0.86±0.01 in August. The fecundity was estimated from 24 randomly collected fish whose length varied from 40.62±1.01 cm to 51.20±0.53 cm, weight from 409.77±7.69 gm to 757.34±6.96 gm and ovary weight from 7.66±0.07 gm to 21.34±0.07 gm. The fecundity was found to vary from 22723.50±396.42 to 45985.83±121.08. The regression equations: log (y) = 3.067 log (x) - .5591, log (y)= 1.168 log (x) + 1.2997 and log (y) =0.624 log (x) +3.8018 as observed for relationship between log of fecundity-log of body length, log of fecundity-log of body weight and log of fecundity-log of ovary weight, respectively in the study indicated that the fecundity of S. aor had a linear relationship with the body length, body weight and ovary weight. Histological study of gonad helped to determine the maturation stages of both male and female. From the histological analysis of ovary, four developmental stages were identified: Early peri-nuclear stage oocytes, late peri-nuclear stage oocytes Yolk vesicle stage oocytes and Yolk granular stage oocytes were identified in ovary during the study period (January to December 2014). Again microscopic observations of testicular germ cells by histological observation revealed presence of spermatocyte (SC), spermatid (ST) and spermatozoa (SZ) stages. The body surface of the male brood fishes were inflamed, reddish and secreted a thick milky white fluid or scum form the body surface during breeding season (July-August). Above discussion indicate that the oocyte development of S. aor is an asynchronous pattern, so fish breed in throughout the year.