Growth and metamorphosis of Rana catesbeiana (Shaw) tadpoles fed live and supplementary feed, using tilapia, Oreochromis niloticus (L.), as a biofertilizer |
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| Authors: | M A Benitez-Mandujano A Flores-Nava |
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| Institution: | Centro de Investigación y de Estudios Avanzados del IPN - Unidad Mérida, Mérida, Yucatán and Programa de Ecología, Pesquerías y Oceanografia del Golfo de México, Universidad Autónoma de Campeche, Agustin Melgar y Juan de la Barrera, Ciudad Universitaria, Campeche, Camp., México |
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| Abstract: | An experiment was conducted to compare growth and timing to metamorphosis of bullfrog Rana catesbeiana (Shaw) tadpoles feeding on phytoplankton and on supplementary feed. Three interconnected, round, 4 m diameter concrete tanks were used in the experiment. Tanks 1 and 2 were stocked with juvenile tilapia, Oreochromis niloticus (L.) to stimulate phytoplankton through faecal fertilization. A third tank remained without fish. Stage 25-Gosner bullfrog tadpoles were placed in 0.042 m3 cages at 1 I?1. Experimental treatments consisted of: (1) tadpoles feeding solely on phytoplankton (P); (2) P + 13% body weight day?1 (bw day1) supplementary feeding (SF); (3) P + 9.75% bw day?1 SF; (4) P + 6.5% bw day?1 SF; (5) P + 3.25% bw day?1 SF; and (6) tadpoles feeding solely on supplementary feed at 13% bw day?1. Final weight was lowest in those organisms feeding exclusively on supplementary feed, followed by those feeding on phytoplankton. Treatments 2 and 3 showed the highest weight (3.65 and 3.64 g, respectively). After 70 days, 50% of the tadpoles in treatment 4 (6.5% bw day?1) reached metamorphic climax, followed by treatment 5 (33%). Only 8% of tadpoles feeding exclusively on live food reached metamorphosis. It is concluded that in the presence of abundant phytoplankton, it is possible to reduce up to 50% of the standard supplementary feeding rate and still have normal growth and metamorphosis. Tilapia represents a good alternative for biofertilization. |
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