A model for tubificid worm (Tubifex tubifex) production and its effect on growth of three selected ornamental fish

. The demand for sludge worms, Tubifex tubifex is increasing with the growth of aquaculture as low-cost live feed in hatcheries and ornamental fish nurseries. The study was conducted to determine the optimal culture medium for T. tubifex worm’s production and to find out the inclusion effects of worms as feed on ornamental fish rearing. Three media-based treatments (T-1: mustard oil cake 20%, wheat bran 10%, soybean meal 10%, rice bran 20%, cow-dung 20%, sand 10%, fish pond mud 10%; T-2: mustard oil cake 10%, wheat bran 10%, soybean meal 10%, rice bran 10%, straw 5%, fish scale, stomach and fin 25%, cow-dung 20%, fish pond mud 10% and T-3: cow-dung 75%, sand 15%, fish pond mud 10%)  with three replications of each were used to culture the worms for 100 days in nine cemented culvert system (160×25×10 cm3). The growth performance of three popular ornamental fishes koi carp (Cyprinus carpio), comet goldfish (Carassius auratus auratu) and goldfish (Carassius auratus) were determined by replacing the commercial feed at different level with tubificid rearing in fiberglass aquarium (45×30×30 cm3) for 32 days duration. Maximum yield (959.23 44.34 mg·cm-2) of tubificid biomass was recorded in T-2 (mustard oil cake-10%, wheat bran-10%, soybean meal-10%, rice bran-10%, straw-5%, fish scale, intestine, stomach and fin-25%, cow-dung-20%, mud collected from fish pond-10%) with a  peak at day 70th.  The fish fed with 50% commercial feed + 50% T. tubifex in TF-2 showed significantly (p<0.05) higher growth and survival performance than other treatments. The mean value of water quality parameters (i.e. temperature, pH and dissolved oxygen) were statistically insignificant (p>0.05) among the three treatments. Approximately 1.83 kg media were needed to produce 1.0 kg tubificid worm in treatment T-2. T-2 media is recommended as suitable media for commercial tubificid worm production and the inclusion of 50 % tubificid worms in the feed can be suggested for the ornamental fish rearing.