Filter-feeding fishes have been examined as biological controls of phytoplankton populations. Although increased phytoplankton biomass resulted in approximately 50% of studies and no effect in 25% (Smith 1988), changes in species composition and dominance have been noted. For example, blue tilapia Oreochromis aureus reduce or eliminated blue-green (Cyanobacteria) and green (Chlorophyta) net phy...

This study provides the first investigation on acquisition of parasites in invasive O. niloticus by parasite species of native Cichlidae from the Igarapé Fortaleza basin, Northern Brazil. There were examined 576 specimens of 16 species of native cichlids and invasive O. niloticus collected in the main channel and the floodplain area of this tributary of Amazon River. The invasive O. niloticus w...

Retinal neurogenesis in fish facilitates cellular rearrangement throughout ontogeny, potentially allowing for optimization of the visual system to shifts in habitat and behaviour. To test this possibility, we studied the developmental trajectory of the photopic visual process in the Nile tilapia. We examined ontogenetic changes in lens transmission, photoreceptor sensitivity and post-receptoral...

We tested whether the fish Nile tilapia (Oreochromis niloticus) in a monosex male group spends more energy and displays an agonistic profile, differently from males in male-female groups. Such differences are expected because males and females should compete for different reproductive resources. An intruder male (MM) or female (MF) was paired with a resident male and agonistic interaction was q...

Pond carrying capacity is largely determined by management practices. Earlier work on semiintensive culture of Nile tilapia (Oreochromis niloticus) using manure or inorganic fertilizers indicated that carrying capacity might reach 2,000 to 3,000 kg/ha (Diana et al. 1991a, b; Knud-Hansen et al. 1991). As stocking density is increased in fertilized ponds, carrying capacity remains largely the sam...

The objective of this paper was to study angling from September, 2002 to September, 2004 in the Lobo-Broa Reservoir, Itirapina, SP (22 degrees 15' S and 47 degrees 49' W). Interviews (total 1,027) with sport fishers were accomplished in the three main fishing sites (Horto, Píer and Praia). This fishing was practiced with a simple fishing rod and reel, mainly in Horto, where the catches and fish...

The Nile tilapia (Oreochromis niloticus) is an important species in aquaculture and an excellent model system for laboratory studies. Functional genetic analysis using this species has been difficult because existing methods for producing transgenics are inefficient. Here we show that the Tol2 transposon system can be used to create transgenic tilapia with high efficiency. We constructed a line...

We measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fis...

The frequencies of mitomycin C and cyclophosphamide-induced kidney and gill erythrocyte micronuclei were compared in Tilapia rendalli and Oreochromis niloticus. Cyclophosphamide (CP) and mitomycin C (MMC) were previously used to investigate fish sensitivity to micronuclei induction in kidney erythrocytes. Fish were treated with a single dose of cyclophosphamide (40 mg/kg) or mitomycin C (2 mg/k...

In this study, the influence of different treatments was evaluated: nonwashing, washing in chlorinated water and washing/soaking in chlorinated water and sodium chloride on the quality of Nile tilapia (Oreochromis niloticus) fillets during storage at 1.0 ± 0.5°C through daily analysis of pH, moisture, and lipids content. Microbiological analysis and growth modeling for mesophilic and psychrotro...