The piranha is growing fast, he's gotten about a fourth to a half of an inch bigger, and Ive been watching him carefully for any abnormal, or aggressive behavior. So far, he hasn't touched a single fish, and is usually schooling with the tetras or searching the sand for any food. I called my local pet store and told them about him, they said they'd take him at any size if he ever got too aggressive, but no refund lol. So he's doing fine... he's a bit chub; eats like a pig. Just got two awesome new decorations from amazon for a really cheap price... at least compared to the stores. Theres a big rocky cave, and a fake wood stump. The Chinese algae eaters love it... so do the jewel fish. My parrot fish is really into it. Just now, I saw him scooping out sand with his bottom lip out of the front of the cave... and he scoots aside these glofish plastic jewels we have that the fish like to push around on the sand. Ive noticed that the fish can show signs of truly remarkable and possibly intelligent behavior. Like mammals, its really cool. My parrot fish is usually the star when it comes to personality. A few weeks ago, I noticed him doing something quite remarkable. Every fish chases others, and they usually have some sort of hierarchical order. My fire mouth is the big guy... he usually just doesn't like any fish getting too close to him, but never has nipped fins or done damage. Anyways, i've noticed that every time he really starts to chase a fish around the tank, Julius ( the parrot) runs in between him and sort of breaks it up. I thought that was curious, but didn't think much of it. Then, as I said, a few weeks ago, I noticed him sort of... its difficult to describe.. lightly chasing and flanking the goldfish? The goldfish usually school and flank each other... sometimes chasing each other around if one has a piece of food. But the parrot from the start always schooled with them, and sifted through the sand with them. He never aggressively chased away the goldies, but started PLAYING with them! It was kind of like a puppy almost. Again, its hard to describe, but when I saw it I immediately distinguished it from normal aggression... it was play!! It was very adorable!! That went on for about a minute, and then stopped when they noticed me watching. Something also very cute and interesting that happened about a month ago was when the fish were sleeping. When I wake up, I just turn on my desk lamp so I can see, and leave the room light off for about ten or twenty minutes, and I can see the fish sleep. They slowly start waking up, usually its the goldfish first... and the oscar is usually the latest. Anyway, normally I find them in their win separate areas of the tank, but that morning, all the bigger fish; the parrot the goldies, the fire mouth, and even the oscar, who never schools or interacts much with the other fish, were huddled together in deep sleep... it was the cutest thing Ive ever seen.