Smart fish catcher / Smart fish catcher

Nowaday,the fishing device can catch both big fishes and little fishes ,
so it can not distinguish that could be catched or not,thus damage the
balance of ecological environment.To solve this problem,a fishing catcher
which can only catch big fishes are designed.Little fishes can swim out
easily from it,so that we can decrease the damage of little fishes ,which
is benefit to the balance of ecological environment.