You've got Piranhas... how cool!!!
I plan to get some large aquarium type thing with some fish at some point in the future.. at the moment I've got some boring 4ft tank with 2 Pangasius and a pleck... I've had them for 13 years... I'm bored of them now lol
Want something with a bit of spunk… now Piranhas would be rather cool… how big are yours and how big is the tank?
I’d love a big inbuilt wall tank with some really cool fish in… maybe a shark too lol… then again… why not go the whole way… I’ll get a dolphinarium in the back garden :grin: 

I have 4 Red Bellied Piranhas (Pygocentrus piraya)
They are 6 months old and about 3 inches long now, and will grow to about 16 inches. The pet shop has some now which are around 8 inches and they look awesome. Once they are in a bigger tank I should be able to get better pictures. Eventually, I'll only be able to keep one because of the eventual size (as big as a rugby ball

).
Yes I've had my hand in the tank

- you have to sometimes, but as long as they are shown respect, and your hand moves slowly, it should be ok! In saying that, once they get bigger I might think twice
They eat bloodworm, fish, beef, sausages, and for a treat they have lumps of chicken which they fight over - Piranha feeding time is an awesome sight especially if they are hungry
Between the 4 of them they will devour a piece of chicken the size of a credit card in about 10 seconds.
I've had them in a 2 foot tank since I got them but I will soon be upgrading to a 4 or 5 foot tank to give them some more room. They need no light (which I have only recently learnt!) as they are used to the murky waters of the Amazon.
The other photo is my 4 foot tank with various community fish in, and a big Plec with his cave