Effects of Two Environmental Best Management Practices on Pond Water and Effluent Quality and Growth of Nile Tilapia, Oreochromis niloticus

Nelson Agbo,Emmanuel Frimpong,Yaw Ansah,Daniel Adjei-Boateng,Stephen Amisah,Hillary Egna

doi:10.3390/su6020652

Abstract

The trajectory of aquaculture growth in sub-Saharan Africa has necessitated closer attention to the use of environmental best management practices (BMPs). Two BMPs in particular, water reuse and floating feeds, are being promoted for adoption by pond fish farmers in sub-Saharan Africa. In this study, we investigated: (1) the effect of water source and feed type on water quality; (2) the effect of water source and feed type on tilapia growth; and (3) the quality of potential effluents from ponds using different water source and feed types. The study was conducted in Ghana using on-farm experiments involving monitoring of water quality and growth of Nile tilapia Oreochromis niloticus for 160 days. Although considered low-intensity production systems, nutrients and solids in the study ponds exceeded levels expected in intensive culture ponds by wide margins, whereas BOD5 was within the range for semi-intensive ponds. Floating feed was associated with higher water quality, especially dissolved oxygen, and higher growth, but water source did not significantly affect growth. Water reuse appears to be a viable BMP for sustainable aquaculture in the region, but the use of floating feed as BMP will depend on the economic profitability of floating feed use.

Highlights

Aquaculture in sub-Saharan Africa is conducted mainly in earthen ponds and is relatively less intensive compared to the same method of food production in Asia, Europe, and North and SouthAmerica
This study describes the effect of water source and feed type on pond water, effluent quality, and growth of Nile tilapia in earthen ponds in Ghana
Total suspended solids, and settleable solids in ponds exceeded the range expected for intensive aquaculture ponds, even though these production systems would be classified as low-intensity or semi-intensive, based on stocking densities

Summary

Introduction

Aquaculture in sub-Saharan Africa is conducted mainly in earthen ponds and is relatively less intensive compared to the same method of food production in Asia, Europe, and North and South. The two BMPs selected for assessment are: (1) water reuse (as contrasted with draining ponds and refilling with new water at the end of each production cycle) and (2) the use of commercial-grade extruded or floating fish feed (as contrasted with sinking feed of the quality made on most farms), the former accomplishing both reduction of effluent volume and nutrient, solids, and oxygen demand whereas the latter primarily serves to reduce nutrient loads These two BMPs have clear alternative practices that are widely agreed to be the status quo, the BMPs are hypothesized to have significant effects on fish growth and pollution potential of ponds, and lend themselves to straightforward experimental manipulation so their environmental effects and economic benefits can be quantified accurately. We investigated: (1) the effect of water source and feed type on water quality; (2) the effect of water source and feed type on tilapia growth; and (3) potential effluents from ponds using different water source and feed types

Study Location

Experiment Setup and Monitoring

Statistical Analysis

Results and Discussion

Conclusions