Three leaf meals, Gliricidia sepium, cassava (Manihot esculenta), and Stylosanthes humilis were screened as feed supplements in the culture of the Nile Tilapia, Oreochromis niloticus. The experiment had four treatments. Treatment A had S. humilis leaf meal incorporated in the feed while treatment B had cassava leaf meal in the feed. Treatment C had Gliricidia leaf meal incorporated in the feed while treatment D was made up of feed formulated without leaf meal (control). Proximate analysis of these leaf meals showed that Cassava leaf meal had the highest crude protein content (26.3%) followed by Gliricidia leaf meal (22.9%) and Stylosanthes leaf meal (19.5%). All the four diets (A-D) were formulated with maize flour, soybean, fish meal, blood meal and the respective leaf meals and crude protein content ranged from 30.57-36.42 %. The diets were distributed randomly to twelve experimental units containing Oreochromis niloticus fingerlings with mean weight range of 2.40-2.55g and fed for twelve weeks. The feed containing cassava leaf meal (Treatment B) gave the best mean weight gain of 3.50 ± 0.01g followed by the feed with Gliricidia leaf meal with a mean weight gain of 2.21 ± 0.06g while the feed with Stylosanthes leaf meal and the control gave mean weight gains of 2.05 ± 0.25g and 1.06 ± 0.03g, respectively. Mean weight gain in treatment B (cassava leaves) was significantly higher (P<0.05) than mean weight gain in other treatments. Mean growth rate ranged from 0.01 ± 0.006 g/day for the control treatment to 0.04 ± 0.001 for the fish fed Cassava leaf meal diet. Specific growth rate (SGR) was also highest in the treatment with cassava leaf meal (1.07 ± 0.11%/day) and lowest in the control. Protein efficiency ratio (PER) was 0.11 ± 0.004 in Treatment B, 0.07 ± 0.001 in Treatment C, 0.06 ± 0.009 in Treatment A and 0.03 ± 0.001 in the control. The food conversion ratio (FCR) was best with cassava leaf feed (3.71 ± 0.19) followed by Stylosanthes (5.51 ± 0.27), Glyricidia (6.17 ± 0.22) and the control (9.48 ± 0.58). FCR, SGR and PER for treatment B (cassava leaves) were significantly better (P<0.05) than the values for other treatments. Percentage survival ranged from 92% with Stylosanthes to 100% with cassava leaf feed. The study showed that leaf meals can be effectively used in the diet of Oreochromis niloticus.

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Tilapia breeds effortlessly in captivity, with this attribute which is considered as the "Achilles heel" of the species, because it predisposes pond systems to overcrowding and low weight at harvest. Efforts to mitigate this shortcoming include mono-sex culture using exogenous hormone to reverse the sex of sexually undifferentiated fish. This is premised on the fact that improvement in the growth by mono-sex culture will lead to shortened production times and a more uniform weight at harvest, which will ultimately benefit the producers. However, the use of exogenous hormones in aquaculture has recently raised concerns about the effect on farm workers, consumers and on the environment. Recently research has focused on the use of substances of plants origin which mimic the action of hormones as a potential approach to achieve sex reversal in fish. Pawpaw (Carica papaya) seed contains phytochemicals that hold great promise as a sex reversal and a reproductive inhibition agent in aquaculture. The purpose of this study was to conduct a systematic review of the relevant literature on the possibility of using a less harmful phytochemicals abundant in the plant to effect sex reversal of sexually undifferentiated tilapia.

Pawpaw seed meal (PSM) can be used as an antifertility agent in animals, however there is no information on its potential toxicological effect on Mozambique tilapia (O. mossambicus). In this study the effect of PSM on the liver, blood haematological and biochemical parameters of O. mossambicus juveniles was assessed to ascertain its suitability as a reproductive suppressant. The PSM was administered at an inclusion level of 10 g and 30 g/kg of a commercial tilapia diet (basal diet, BD) for 30 and 60 days, respectively. The potential toxicological effect was assessed by determining the extent of change in the normal haematological (RBC count, haematocrit, haemoglobin, MCV, MCH, MCHC, thrombocyte count, absolute WBC and differential cell counts) and biochemical (cholesterol, total protein, albumin, globulin and glucose) parameters. Haematological and biochemical profiles of different treatment groups did not differ throughout the course of the investigation. Liver weight and hepatosomatic index values of the treated fish were comparable to those of the control. The absence of any effect of the blood parameters measured in this study also indicate that PSM has no compromising influence on the immune system of the fish, indicating that PSM can be considered as a safe alternative to induce masculinization in Mozambique tilapia, and therefore act as a reproductive inhibitor.