PURPOSE: To automate a series of works for forming a fish-tray agglomerated body and economize the labor for fish-tray agglomeration, by piling, in multistages, a plurality of fish-trays arranged in plane form, via a plurality of rod members arranged in parallel.

CONSTITUTION: A fish-tray agglomerated body forming mechanism 1 comprising a conveyor 1A for collecting in a two-dimensional group a prescribed number of fish-trays (P) is arranged, and when the formation of a fish-tray agglomerated body (m) in the mechanism 1 is detected by a sensor 1C, said agglomerated body (m) is pushed-out into a fish-tray agglomerated-body unit forming mechanism 4 by a pusher 3. In said mechanism 4, a plurality of rod members B arranged in parallel are supplied beforehand from an automatic rod-member arranging and feeding mechanism 2, and the fish-tray agglomerated body (m) is loaded onto said rod members B, and a fish-tray agglomerated-body unit M is formed. Said unit M is transported to stage-pilling mechanism 7A and 7B through the piling conveyor mechanism 6 in a fish-tray agglomerated-body forming mechanism 5, and said units M are piled into two stages or more, and thus a fish-tray aggomerated body is formed.