Same here . When we had chicken for supper I always grabbed the sack of giblets and took out the heart and liver and hid them in the freezer for my piranhas . I would shave little pieces off to feed him and I had him for a couple years until he jumped out somehow . The top didn’t stop him and he got to about six inches in that twenty gallon . I started out with three but one disappeared entirely a month in and the other a month or so later , all but his bony head . Gruesome creatures preying on each other.