Untitled

Abstract

Influences of two types of substrates, natural (macrophyte, Pistia stratiotes) and artificial (plastic screen) were evaluated at 3 differrent densities (10, 20, 30%) on periphyton development, water quality and growth performance of jaraqui (Semaprochilodus insignis). Fish of average initial weight 1.46-1.69 g and length 4.15-4.26 cm stocked at 1/m 2 in 46 m 2 masonry tanks were grown for 120 days. The tanks were fertilized with urea, triple superphosphate and wheat bran. The types and densities of substrates tested did not drastically influence water quality. Natural substrate harboured higher periphyton biomass (1.48±0.09 mg/cm 2 ) as well as species diversity (28 genera) than the artificial substrate (0.84±0.12 mg/cm 2 , 20 genera). Fish in 10% and 20% artificial substrate and 20% natural substrate treatments showed better mean values of body weight (24.64, 23.86, 29.26 g respectively) on termination of the experiment. Fish survival was the lowest in 30% natural substrate (84.1%) and highest in 10% artificial substrate (94.2%). Higher fish biomass was recorded in 20% natural and 10% artificial substrate treatments (25.05 and 21.71 g/m 2 ), which amounts to a four-month yield of 250 and 217 kg/ha in the two treatments.

Periphyton Growth on Three Bio-substrates and Its Influence on the Performance of Jaraqui (<i>Semaprochilodus insignis</i>)

“…The difference in values could be attributed to both the number and species of algae present. Phytoplankton population of periphyton from the three substrates belonged mainly to the families Chlorophyceae, Cyanophyceae, Bacillariophyceae and Chrysophyceae as reported in earlier studies (Gangadhar and Keshavanath, 2008;Tortolero et al, 2016). There was significant difference in the abundance of periphyton zooplankton, the numbers being 2 and 3 times higher in bamboo periphyton than that of ambay and leucaena.…”

“…In recent years, periphyton-based fish culture is developing as an alternative to systems with low input supplemental feeding, due to the high cost of artificial diets. It results in increased fish/prawn production (Mridula et al, 2005;Jana et al, 2006;Garg et al, 2007;Asaduzzaman et al, 2010, Keshavanath et al, 2015Bharti et al, 2016;Shilta et al, 2016;Tortolero et al, 2016;Kumar et al, 2017), simultaneously addressing environmental concerns through effective recycling of nutrients from the aquatic system. Higher fish yield from such systems is enabled by the nutritional contribution of periphyton growing on the substrates and also better survival since substrates act as shelters for fish.…”