Artificial Propagation of Tench (Tinca tinca) to Fingerling Size in 1994

The tench, predominantly lacustina fish, lives in stagnant or sluggish water-bodies with silt covered bottoms. The artificial propagation aimed to produce fish fries for re-stocking programme in natural ecosystems. The brooders comprised of 130 female and 80 male fish. The individuals weight of fishes ranged between 0.2 - 0.45 kg. The female and male fishes caught from wild stock, were separated and kept in two earthen ponds. The biotechnique of carp production were used for culture process. The eggs stripping conducted 8 times according to the ripeness of the brood stock. 60 femal spawners were injected by the Gonadotropic hormone from pituitary glands of carp fish to induce the brooders. The used dosage was between 3-8 mg per kg of body weight, applied in two doses. With only one treatment, 6-8 mg hormone were injected per kg of body weight. Water temprature were 20-24°C in June. Male spawners were treated only once with 3-4 mg of the hormone per kg of body weight. The experiment showed, in two application the effective dose of hormonewas 6-8 mg, that helped 80-100% of the female fishes to discharge eggs. With one treatment, the efficiency of hormone was 7-8 mg, which induced 80-85% of the female spawners to release eggs. The eggs were put in saline carbamid solution mixture after fertilization to eliminate stickness and then washed with pure water. The previous washing treatment took 45-75 minutes and the next one 25-45 minutes. The eggs fertilization rate were 70-85%. Incubation of eggs up to the hatching in Weise jar were 2-2.5 days. The survival rate of the hatched fries were 85-95%, and the size of newly hatched larvae were 4.5-5rnm. The larvae were placed into large Zuge glass. After 4-5 days the young fishes began to feed actively. The diameter of dry eggs were 0.52 - 4 mm and the swelled ones 0.8 - 0.65 mm. Number of eggs/spawners (working fecundity) were 10848 - 17710, and relative fecundity were between 80-350 eggs per 1 gram of body weight. Color of the eggs were bright yellow and greenish yellow.

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