Isolation, identification and culture of the marine rotifer Colurella adriatica Ehrenberg, 1831 (Family: Lepadellidae) from Andaman & Nicobar Islands: A promising live feed for larval rearing of high value shellfishes and finfishes

An extremely small rotifer was isolated from the micro zooplankton samples collected during February, 2014 from Havelock islands of Andaman and Nicobar Islands. The species was identified as Colurella adriatica Ehrenberg, 1831 (Family: Lapadellidae). Its lorica length under culture period ranged from 47.530 to 98.868 μm and width from 34.308 to 56.277 μm. The size of the eggs, neonates and adults are also documented. Comparison of size of C. adriatica with Brachionus plicatilis (L type) and B. rotundiformis (S and SS type) revealed that C. adriatica is smaller in length and width than the SS-type rotifer which is currently used as a first feed in marine tropical fish larval rearing. However, the larvae of many marine food fishes including groupers and high value marine ornamental fishes are unable to consume the SS-type rotifers as a first feed due to their extremely small mouth gape. The culture of C. adriatica was carried out using Nannochloropsis oculata Diet-I), N. oculata and yeast (0.01g/litre) (Diet-II), Yeast (0.01g/litre) alone (Diet-III). Average population density of C. adriatica with these diets reached a maximum of 1000 nos. of individuals /ml on 10th day of culture on feeding with Diet-I; 950 nos. /ml on 14th day (Diet-II) and 650 nos. /ml on 15th day of culture (Diet-III). Diet I &II and Diet II &III did not show any significant difference (P>0.05) whereas, Diet I and III showed significant difference (P<0.01). Preliminary studies of C. adriatica as a feed to the larvae of Stenopus hispidus, Lysmata amboinensis and Pomacentrus caeruleus showed better survival than larvae fed with B. routundiformis during first phase of larval rearing.