T. zillii fingerlings were acclimated for 14 days in concrete tanks during which they were fed with a commercial diet. After acclimation, 10 male and 10 female T. zillii (mean weight, 40g) were stocked in each of 15 concrete tanks (2 x 2 x 1.25m) supplied with 400 litres of fresh water (water temperature, 27 oC; pH, 7.3; alkalinity, 50 ppm; dissolved oxygen, 7.6-7.9 mg/L). The treatments were replicated thrice and fish were fed at 4% body weight/day in two instalments at 0900-0930 h and 1700-1730 h for 60 days; after which they were removed, sorted by sex and weighed. Fish samples were randomly taken from each treatment, dissected, and the testes and ovaries removed for sectioning and histological examination. The testes and ovaries were fixed for 24 hours in formalin-saline solution made of equal volumes of 10% formalin and 0.9% NaCl solution. Histological sections of 8µ thickness were prepared following standard procedures. Photomicrographs were taken with Leitz (Ortholux) microscope and camera and compared with those of Morrison et al. (2007).
RESULTS AND DISCUSSION
Histology of testes in T. zillii fed varying dietary levels of neem leaf meal
Sections of testes in T. zillii fed 0g NLM/kg diet (control diet) showed normal testicular tissue architecture and sperm cells distribution (Figure 1). Fish fed 5g NLM/kg diet showed alterations in the testicular architecture and cystic seminiferous tubules (Figure 2). In fish fed 10g NLM/kg diet, sections of the testes showed severe testicular atrophy (Figure 3), while fish fed 15g NLM/kg diet, showed cystic tubules and atrophy in the testicle (Figure 4). In fish fed 20g NLM/kg diet, sections of the testes showed severe testicular tissue atrophy, sperm cells disintegration and necrosis (Figure 5).