Very little is known about lumpfish nutritional requirements even though there are now commercial diets available that are either suitable or specifically marketed for lumpfish. Researchers at the University of New Hampshire (UNH), the USDA National Cold Water Marine Aquaculture Center, and the University of Maine are conducting a series of juvenile lumpfish feeding strategies studies. The first of these feed studies focused on juvenile lumpfish nutrition and was conducted in 2020-21 at the UNH Coastal Marine Laboratory.
A common garden experiment was conducted using 6- to 8-month-old lumpfish, stocked into 0.01-m3 (10 liter) tanks at initial densities of approx. 10g/L in a flow-through, ambient temperature sea water system. This protein to energy study examined two different crude protein levels (50, 55%) and three different fat levels (10, 15, 20%) in feeds. Lumpfish were evaluated using six experimental diets and a control diet. Experimental diets were formulated by the USDA Aquaculture Research Service at the Bozeman Fish Technology Center in Bozeman, Montana with animal ingredients (fishmeal and poultry-by-product meal) as the main protein source and fish oil as the main lipid source. The control diet consisted of a standard commercially available diet (Skretting Europa, 55/15) that is used in US facilities. In addition, a salmonid diet, BioTrout, consisting of 47% plant-based protein, 24% lipid, was tested too. Fish were fed at 3% body weight/day for 10 weeks and survival, growth, and aggression measured.
In general, varying animal protein and lipid concentrations did not negatively affect growth, survival, or fish aggression of juvenile lumpfish. In all treatments fish survival was >98%. Overall mean percent growth ranged from 633 to 781%, and FCR ranged from 1.10 to 1.23. The use of plant-based protein (and a diet formulated for salmonids), however, suppressed juvenile lumpfish growth; overall mean percent growth was only 394% and FCR was 1.54.