U radu su izneseni petogodšnji rezultati i problematika kaveznog uzgoja soma u hidroakumulaciji Modrac. Jezero je površine 1 700 ha, dubine do 18 m, a nastalo je gradnjom brane na rijeci Spreči kraj Tuzle.
Fizikalnokemijski parametri vode varirali su u pogodnim granicama, osim u prvoj godini uzgoja, kada je zbog nagla zahlađenja došlo do inverzije vode, što je uzrokovalo drastično smanjenje koncentracije kisika i pomor ribe. S obzirom na temperaturu vode, razdoblje hranidbe riba kreće se od 155 do 174 dana. Za razliku od uzgoja u ribnjacima, hranidba traje od sredine svibnja do polovice listopada.
Gustoća nasada u kavezima iznosila je 9 do 32 kom/m3, a masa nasada od 2,35 do 6,39 kg/m3. Ukupni prirast ribe po m3 varirao je između 2,39 i 12,02 kg. Pojedinačni dnevni prirasti soma kretali su se od 2,77 do 5,83 grama. Tako skromni proizvodni rezultati posljedica su mnogih problema koji su se javljali u tijeku uzgoja, a najbitniji su neprikladna hrana i nedovoljna količina kvalitetnog mlađa.
Gubici ribe kretali su se od 1,54 do 34,1%, a nastali su zbog ihtioftirioze, kanibalizma, asfiksije i bježanja ribe iz kaveza nakon oštećenja mreža od štakora i vidri. Unatoč visokim gubicima nižim prirastima nego u ribnjacima, proizvodnja soma u kavezima zbog kvalitetnog mesa i izvoza na zapadno tržište osigurava ekonomsku rentabilnost.Presented are the results of a 5-year study and the problems of cage-culture of the sheat fish in the hydroaccumulation Modrac. The lake has a surface area of about 1700 ha, a depth of 18 m, and was created by the building of dams on the river Spreča near Tuzla. Physico-chemical water parameters varied in acceptable limits, except in the first year of culture, when because of a sudden lowering of temperatures water inversion occurred, which caused a drastic oxygen decrease and death of the fish. Depending on the water temperature the feeding period for the fish ranged from 155 to 174 days. Differing from the culture on fish farms the feeding lasted from mid-May to mid-October. The stock density in cages was 9-32 per/m3, and stock weight from 2.35 to 6.39 kg/m3. The total growth rate of fish per m3 varied between 2.77 to 5.83 grams. This kind of modest production results is due to a range of problems which occurred during the culture, the most significant being unsatisfactory food and not enough quality fry.
Fish losses ranged from 1.54 to 34.1%, and came about due to the ichtyophirosis, cannibalism, asphyxiation and because of fish escaping from the cages after damage to the nets from rats and otters. Despite high losses and a lower growth rate than on the fish farms, the production of the sheat fish in cages, because of the quality of meat and export to the western market, ensures an economic rentability
