( od rn iy ne “a: EGS “ . oy. - a "he 7 we f ee Ve 7 From mid-February to the end of March the techniques of igig -* - + 2. rearing a marine flat fish, Parophrys vetulis, in non-sireulating salt water aquaria were studied. \ Best results were obtained by placing one fish to an aquarium, The size of the fish ranged from 133-147 mm. The aquaria used were 8" x 1) 3/4" x 8 and were set in a hatchery trough with running water for cooling, During April the temperature was 52 - 53°F, — Air was bubbled through the water in each aquarium by means of a Marco air pump with a carborundumtip at the terminus of each air line, This was the only means of circulating the water, not changed during April, Water was Also added to each aquarium was sand, either one mussel (Mytilus edulis) or one clam (Macoma secta), one shoot of eel grass and one small bit of algae, Ulva sp.. Fresh minced clam was apparently a satisfactory food and was preferred to several others offered. | By the first of April it was believed that knowledge of caring for these animals was sufficient to conduct an experinent. aquaria as described above were available. Six In aquarium #2 the sand was replaced with active Bikini mud that had been ground in - @ particle grinder. It would have been well to have had a control aquarium for #2 with non-active Bikini mid ground to the same fineness but such waa not available. This was not a food experiment but an experiment to observe the effect of the md upon a fish, The fish was fed and cared for in the same manner as those in the other aquaria, Since flatfish are bottom dwellers and usually spend @ great deal of their time burried in the bottom, always 50% and as much as 95% of the surface of the fish was in direct contact with the md, Counts of the Bikini mad uncorrected for self absorption and 6