Get them on the shallow bit of the water and place a fish trap but you have to sit their feeding it however a pack of these are useful but one will die so keep them safe also watch out they do pack a punch
Tamable using fish baskets from aberration. They attack the baskets once placed. It is a good strategy to pen then in with fence foundations and walls, or kite them to a pen. Place your basket on the other side of the wall and catch.
A piranha is tameable in Abberation using the fish trap. It has to swim into it. Once you release it from the fish trap, it will be tamed. Great tame in packs, they can kill a good amount of low to mid level groups of players.