"I'm having Fish tonight!.."

My family a monster of a fish (a patin) that my kids call Krepek. Having grown to 8 inches, he had already outgrown his 2 foot tank. We bought a 4 foot tank for him and and his buddy bandaraya, but he looked pretty lonely going round and round in a big empty tank. One day, we went out to the store and bought a couple of 2 inch jelawats and a couple more 2 inch patins. The store owner said, that it was safe to have these unless our patin was more than a foot long. Well, we fell for it. To be sure, my son googled care of the patin and found the recipe for making good patin dishes.
the six of them lived happily in the tank until one morning we found one of the tiny patins missing. My son then told us during the night he found Krepek extremely agitated, splashing around in the tank. I guess, he proved his carnivorous streak then. The remaining Patin, Keropok, was now fond of gathering the plants together into a clump and floating within them all night. We wondered if it were nesting instincts . He would float there quietly, just a bit of his snout on the surface, following the flow of the current in the tank; many times we thought that maybe he's dead, and we'd stick our finger on his snout and find him shooting off into the depths of the tank.
Well, about two nights ago, my son told me again, he heard the water splash, except this time, he saw the carnage. He saw Krepek chase the poor thing, catch up with him, and...
Well,.. we really thought that they'd learn to live together, like the store keeper said. Then again, these are carnivores, and when the moment comes, the call of the wild can be too strong to resist.