Title: Alternative sources of protein in feed for fish: a case study on Atlantic cod fry (Gadus morhua)

Commercial aquaculture is growing, thereby increasing the demand for aquaculture feeds. Traditionally, these feeds have been based on animal protein. However, due to cost and availability considerations, it is inevitable that more plant protein supplements will be utilised in the feeds in the future. Plant proteins are more cost effective than animal protein supplements. The increased acceptability and utilisation by the feed industry will be dependent on reliable nutritional research. Plant protein supplements are being used to some extent in all aquaculture feeds. Soybean meal is the most extensively evaluated and most commonly used. This project is divided into two parts: firstly, a review of the protein component in the feed for carnivorous and omnivorous fish, and secondly, a case study where the effects of substituting alternative sources of protein on growth and survival of cod fry (Gadus murhua) are investigated. Six isocaloric and isonitrogenus diets were tested, using protein of different origin. Superior fishmeal (LT) was used as reference diet and replaced partly or totally with special fishmeal (NSM), standard fishmeal, Corn Gluten Meal and HYPRO Soybean meal. Fish (initial weight 28 ± 0.5 g) were distributed among 18 circular 90 L fibreglass tanks, 50 cod in each tank. Each tank was randomly assigned diets in triplicate. The weight and length of the fish were measured every four weeks. Partial replacement of SUP with SPES; STANDARD; MGM and HYPRO or a full replacement with Standard did not result in a significant decrease in specific growth rate (SGR) in cod fry during the first four weeks of the trial but there was a tendency to reduced growth. The present observations suggest that it is possible to substitute high quality fishmeal with different protein in the feed for cod fry.