No abstract

The overall objective of organic and inorganic fertilizers is to increase fish farm productivity. A common practice in fish farms is the fertilization of ponds to enhance algae growth and promote the production of zooplankton suitable for larvae. Several studies carried out in freshwater environments have established that the growth of phytoplankton may be controlled to a large degree by the limitation of nutrients, availability of light and the composition and abundance of zooplankton (Basualto et al., 2006).

The present study was carried out to evaluate the phytoplankton community and water quality in four parallel fishponds (FP1 to FP4) during one year. Some abiotic parameters of water column and phytoplankton was sampled in four sites, one in each fishpond. Similarity analysis showed that FP2 fishpond was markedly different for the others ponds with regard to phytoplankton community. Conductivity, orthophosphate, temperature, TSS and hardness parameters were significantly different (p<0.05) between fishponds and all limnological parameters were significantly different (p<0.01) among period (months). Organic matter and phosphorus of the sediment were significantly different (p<0.01) only among fishponds. In current study Chlorophyceae and Bacillariophyceae occurred in most months. Cyanobacteria density in April and May was higher in all fishponds, at FP3 represented 71.4% in April and FP1 represented 78.7% in May of total reported, with chlorophyll-a content lower than 41 mg.L -1. The physical and chemical parameters of fishponds water constituted relations between the parameters and algae occurrence. The present study however, indicated that Cyanobacteria was more frequent in the fishponds after the fish grow-out period (April), and the water quality should be monitored more frequently in this period, due to the high total phosphorus, orthophosphate and chlorophyll-a contents.Keywords: algae, aquaculture, physical and chemical parameters, water quality. Variação sazonal dos parâmetros bióticos e abióticos em tanques de piscicultura com disposição paralela de região neotropicalResumo O presente estudo avaliou durante um ano a comunidade fitoplanctônica e os fatores abióticos da água de quarto tanques de piscicultura (FP1 ao FP4) com disposição paralela. Alguns fatores abióticos da água e do fitoplâncton foram amostrados em quarto pontos, localizados um em cada tanque de piscicultura. . Os parâmetros físico-químicos da água dos tanques de piscicultura apresentaram relação com a ocorrência do fitoplâncton nestes sistemas. Os resultados deste estudo indicaram a maior frequência de Cyanobacteria no período após a engorda de peixes (abril) necessitando maior monitoramento da qualidade da água devido aos altos teores de fósforo total, ortofosfato e clorofila-a observados neste mês (abril) Palavras-chave: alga, aquicultura, variáveis físicas e químicas, qualidade da água.

Aim Examining whether small-scale tilapia cages have a potential influence on water abiotic parameters in a pond of a flow-through system. Methods Tilapia cages were installed near the pond water outlet. Samples for determination of abiotic parameters were monthly collected during eight months at five sampling sites: near three inlets receiving effluents from other fishponds (IW12, IW6 and IWM, the latter opening in a macrophyte bed), close to the cages in the open-pond (CC) and close to the water outlet (WO). The data were analyzed using Principal Component Analysis (PCA). Results The first PCA axis (70% of the data variability) was related to eutrophication and the second axis (20%) to the dependence of nitrifying bacteria on substrate availability. The sampling sites IW12, CC and WO showed high eutrophication levels. The lowest total phosphorus content, total suspended solids, hardness, alkalinity and conductivity and the highest dissolved oxygen were observed in the macrophyte bed area (IWM). Fish cages significantly increased total phosphorus content, conductivity, alkalinity and hardness in relation to the macrophyte bed inlet. Water outlet abiotic parameters were similar to near cage water. Conclusion The integrated cage-pond technology may be utilized in flow-through systems if incoming water quality (mainly in the site W12) is improved. Cages should be positioned closer to the pond center where it is deeper allowing higher flow-through and dispersion of uneaten feed residues and feces from the cages. This would avoid their deposition beneath cages and reduce their negatives influence on water quality entering the next fishpond (WO), and therefore not impair fish performance.

ABSTRACT.A laboratory culture of Ankistrodesmus gracilis algae was evaluated by studying the biology of the species and its chemical composition in a traditional medium (CHU 12 ) and in two alternative culture media, NPK (20-5-20) and macrophyte (Eichhornia crassipes) + NPK, in three different types of recipients (fiberglass, carboy and plastic bag).

The growth rate and percent survival of Betta splendens when submitted to formulated diet and live food treatments are evaluated. The three different diets were used and designated as: formulated diet (basal diet); live food diet (plankton) and mixed diet (formulated diet with plankton). The live food diet contained plankton belonging to an open pond. High mortality was reported with live food (plankton) treatment whereas higher percent survival occurred with formulated diet. Highest specific growth rate, weight gain and final weight were reported in the mixed diet treatment and were significantly different (p<0.01) from those in formulated diet and live food treatments. The gut contents of B. splendens in mixed diet and live food treatments comprised, Rotifera and Bacillariophyceae species in high percentages or rather, over 78% of total organisms. Lecane sp. was the most ingested zooplankton species by B. splendens in both treatments (mixed diet and live food), with the phytoplankton species Asterionella sp. and Melosira sp. respectively in mixed diet and in live food, respectively. Results indicated that the formulated diet influenced the water parameters dissolved oxygen, total suspended solids, total dissolved solids and pH. The live food in the open pond was not enough to improve the growth rate and percent survival of B. splendens. The growth performance of B. splendens; had the best results with mixed diet which was capable of maintaining species's survival (82%) and development in artificial conditions, benefiting the culture management of ornamental fish.Keywords: ornamental fish, plankton, formulated diet, growth, aquaculture.Alimentação do peixe-de-briga, Betta splendens (Regan, 1910) em tanque externo de cultivo: dieta natural e formulada ResumoFoi avaliado o crescimento e sobrevivência de Betta splendens, quando submetidos à dieta formulada e alimento vivo. Foram utilizadas três dietas experimentais e designadas como: dieta formulada (ração); alimento vivo (plâncton) e dieta mista (ração com plâncton). O plâncton pertence ao tanque externo de cultivo. Alta mortalidade foi observada no tratamento com alimento vivo (plâncton) e a mais alta sobrevivência na dieta formulada. No tratamento com dieta mista foram observadas as maiores taxas de crescimento específico, ganho de peso e peso final, sendo significativamente diferentes (p<0,01) dos outros tratamentos. No conteúdo do trato digestório do B. splendens nos tratamentos dieta mista e alimento vivo, as espécies de Rotifera e Bacillariophyceae foram encontradas acima de 78% do total de organismos observados. Lecane sp. foi a espécie de zooplâncton mais ingerida por B. splendens em ambos os tratamentos (dieta mista e alimento vivo) e de fitoplâncton foi Asterionella sp. (dieta mista) e Melosira sp. (alimento vivo). Os resultados do presente estudo indicaram que a dieta formulada (ração) influenciou alguns parâmetros da água, como oxigênio dissolvido, sólidos totais solúveis, sólidos totais solúveis, sólidos totais suspensos e pH, e o alimento vi...

Effects of biological treatments in the water quality in neotropical fishpondsThe aim of this study was to investigate the effects of the aquatic macrophyte (Eichhornia crassipes) and periphyton communities on the neotropical fishponds water quality, and to determine the ability of such communities to remove potential pollutants from the fishponds, making them interesting tools for the maintenance of desirable water quality in aquaculture under continuous water flow. In general, the biological treatments used in this study showed a positive effect in reducing BOD 5 , orthophosphates, total phosphorus, conductivity and thermotolerant coliforms from the water column and also decreasing organic matter, Cu, Fe, Mn and Zn, from the sediment. The differences in physical and chemical properties of the water column and sediment between the treatments showed an improvement in the overall water quality when the treated fishponds are compared with the control fishpond. The best growth rate performance of Nile tilapia (Oreochromis niloticus) occurred in the fishpond with periphyton treatment.

Aim:The present investigation aims at evaluating attention to the occurrence and abundance of planktonic communities in fishponds and their relationships to the management employed; Methods: Seven fishponds (V 1 -V 7 ) fertilized with different treatments were analyzed by monthly sampling, taken between July and December/07, during both dry and rainy seasons; Results: Euglenophyceae and Chlorophyceae were most representative during the studied period. In the fishpond with organic fertilizer Cyanobacteria was more than 65 and 90% of total phytoplankton abundance in September and August, mainly represented by Microcystis sp. (14,595 and 22,500 ind.L -1 , respectively). An inverse relationship occurred between Copepoda and Cladocera, and Copepoda and Rotifera were present in all fishponds during the both seasons. Diversity (H') and species richness was low and equitability indices generally showed the highest values for zooplankton. The lowest values were observed for phytoplankton during the rainy season; Conclusions: The use of organic fertilizer and the random emptying of the fishponds affected directly and species diversity and richness, with dominance of Cyanobacteria emphasizing the need to adopt a management technique to increase fishponds productivity and consequently, fish production.Keywords: phytoplankton, zooplankton, fishponds, management.Resumo: Objetivo: O presente estudo objetivou avaliar a ocorrência e abundância da comunidade planctônica em viveiros de piscicultura em função do manejo adotado; Métodos: Foram estudados sete viveiros (V 1 -V 7 ) com diferentes tratamentos de fertilização, com amostras realizadas mensalmente de julho a dezembro/07, em duas épocas do ano: seca e chuva; Resultados: Em geral, Euglenophyceae e Chlorophyceae foram as mais representativas ao longo do período estudado. No viveiro com fertilizante orgânico, Cyanobacteria representou mais de 65 e 90% do total de organismos fitoplanctônicos ocorrido em setembro e agosto representado principalmente por Microcystis sp. (14.595 e 22.500 ind.L -1 , respectivamente). Relação inversa foi observada entre Copepoda e Cladocera, porém Copepoda juntamente com Rotifera estiveram presentes em todos os viveiros nas duas estações. A diversidade (H') e riqueza de espécies apresentaram baixos valores e, o índice de equitabilidade, em geral, foi elevado para o zooplâncton. Os valores mais baixos de equitabilidade para o fitoplâncton foram observados durante a estação chuvosa; Conclusões: O uso de fertilizante orgânico e o esvaziamento aleatório dos viveiros influenciaram diretamente na diversidade e riqueza de espécies, com dominância de Cyanobacteria, enfatizando a necessidade de adotar uma metodologia de manejo para aumentar a produtividade dos viveiros e consequentemente, a produção de peixes.Palavras-chave: fitoplâncton, zooplâncton, viveiros, manejo. Biological LimnologySipaúba-Tavares, LH., Millan, RN. and Amaral AA. Acta Limnologica Brasiliensia710 (V 2 ) and 6,550 m 2 (V 7 ), and mean depth was 1.50 m. Fishponds' water supply ...