Piranha hiding?

Question
QUESTION: Help! One of my little red belly piranha won't come out of hiding in the driftwood! Right now I have three of red bellied piranhas, and each of them are  about an inch long. I just tested the water parameters, and they are fine. the two others are swimming back and forth like no tommorrow.They are in my 20 gallon right now. YES I KNOW THAT IS TOO SMALL!! they will only be in there for a little while longer, as my 75 gallon tank is only about three weeks into the cycling process, and I don't want to rush things. The piranha hardly comes out, and I barely see him eating. What is wrong with him, and how can I fix this?!

ANSWER: Hi Daniel,
Sounds like you have a shy piranha!

But first I'd make sure to check and see if the piranha has any signs of disease. If you can manage to get a good look at him make sure to look for ick parasites, signs of bacterial or fungal infections or injuries. Any spots or discolorations would be concerning.
Its also possible that the other bolder piranhas are bullying him and he is the most timid individual out of the group.

You could try providing shady spots in the aquarium by floating plants on the surface which can help shy fish relax better.

Also, if you haven't had your piranhas for long. This one may still be going through the 'adjustment period' till he gets use to his new environment.

Still, as I've mentioned Id keep a close watch on him and make sure he isn't coming down with any illness.

Best of luck and I hope this helps!
Karen~

---------- FOLLOW-UP ----------

QUESTION: Thanks for the input! Ok well I examined him, anD he does not appear to have any ilnesses. I checked the water parameters, and they are fine. I first bought this little redbelly about a week before I put the other two in, so could this be the problem? They all seem to be the same size, and I have never witnessed any kind of bullying between any of them, plus no signs of nipped fins. I usually don't turn the lights on in that tank either. Could it be he just needs time to "fit in with the new crowd"?

Answer
You're welcome!

Ah, I'm glad to hear he doesn't have any signs of sickness. I believe perhaps this little guy just needs time to adjust and fit in with the new crowd as you have said. It very likely is intimidating for him and I'm sure he's being cautious before venturing out with the other ones.

Just make sure some food gets to him at feeding times so he doesn't go hungry.

I'm sure he'll settle eventually. Its interesting that Red-bellied piranhas are often one of the shyest species of piranha and can be skittish so take that into consideration as well.

Best wishes as always!
Karen~