LARVAE REARING TANK AND CIRCULATION SYSTEM FOR FISH CULTURE

摘要

A larvae rearing tank and a water circulation and filtration system associated therewith which provides a high rate of water exchange in the larvae tank with minimum turbulence and water flow in the direction of the tank walls, thereby to provide optimum conditions within the tank for insuring survival of the fish larvae therein. The larvae tank includes a granular layer of filtrant material supported in spaced relation from its bottom end, an outlet pipe for discharging water from the bottom end, and an input reservoir for supplying water thereto above the level of the granular filtrant material. The reservoir is embodied in a container of smaller cross-sectional area than the larvae tank which is positioned within the tank and has a plurality of horizontally extending hollow rods which are sealed on the ends thereof and have a plurality of small holes therein through which the water is transferred from the reservoir to the larvae tank with an initial circular flow pattern. Water from the outlet of the larvae tank is pumped to a sump positioned at substantially the same level as the larvae tank, and from there it is pumped through a filter system and discharged into the top of the input reservoir, whereby the input rate of water being delivered to the larvae tank is determined by the pressure head in the input reservoir created by the height of the filtered water therein which, in turn, is controlled by a valved head-relief line leading to the output sump.