Assessment of Hydroponically Grown Macrophytes for Their Suitability as Fish Feed

A E Ghaly,A M Snow

doi:10.3844/ajbbsp.2008.43.56

Abstract

Water hyacinth, water lettuce and parrot's feather plants were examined for their ability to remove nutrients from aquaculture wastewater at two retention times. During the experiment, the aquatic plants grew rapidly in the hydroponics system and appeared healthy with green color. At hydraulic retention times (HRTs) of 6 and 12 days, the average water hyacinth, water lettuce and parrot's feather yields were 83, 51 and 51 g (dm) m-2 and 49, 29 and 22 g (dm) m-2, respectively. The aquatic plants were able to significantly reduce the pollution load of the aquaculture wastewater. The TS, COD, NH4+-N, NO2--N, NO3--N and PO43--P reductions ranged from 21.4 to 48.0%, from 71.1 to 89.5%, from 55.9 to 76.0%, from 49.6 to 90.6%, from 34.5 to 54.4% and from 64.5 to 76.8%, respectively. Generally, the reductions increased with longer retention times and were highest in compartments containing water hyacinth followed by compartments containing water lettuce and parrot's feather. The nutritive value of the three wastewater grown plants was assessed to determine the suitability of using the plants as a component in fish feed. The three wastewater grown plants did not contain sufficient amounts of protein and fat to meet the dietary requirements of fish and shellfish. They also contained high concentrations of K, Cu, Fe, Mn, Se and Zn, which can lead to reduced feed intake, weight gain and growth rates in fish and shellfish.

Highlights

Aquaculture is defined as the controlled cultivation meals on the global markets, the aquaculture industry is and harvest of aquatic organisms
Aquaculture, good nutrition is essential for the The sustainability of the aquaculture industry depends production of a healthy, high quality product. on the reduction of wild fish inputs into fish feed[6]
Due to their high hyacinth, water lettuce and parrot’s feather plants on nutritional content, marine protein meals such as fish wastewater from a recirculating aquaculture system as a meal, squid meal and shrimp meal have long been the component of fish feed as determined by their nutritive main protein sources used in feeds for most aquaculture value

Summary

Introduction

Aquaculture is defined as the controlled cultivation meals on the global markets, the aquaculture industry is and harvest of aquatic organisms. The primary aim of this study was to evaluate the cost of aquaculture production, with protein being the feasibility of using hydroponically grown water most expensive component[2,3,4]. Due to their high hyacinth, water lettuce and parrot’s feather plants on nutritional content, marine protein meals such as fish wastewater from a recirculating aquaculture system as a meal, squid meal and shrimp meal have long been the component of fish feed as determined by their nutritive main protein sources used in feeds for most aquaculture value. Marine meals are generally incorporated into evaluate: (a) the effect of retention time on plant growth

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