thanks everyone for the comments. Man you guys really hate my gravel
. I kind of want to change it to sand but I don't really know how to do it properly. I also don't know how you would get all that gravel out without draining the tank, cause it would look stupid if some of the gravel was left in. Also an answer to the how long have I had the two exos in there, the answer is 1 month. My pleco also been in there for a month. My piranhas are very well fed that could be why. Anyways if you guys have any Idea what type of sand I should get and how to do it I might think about it. Anyways thanks for the complements on my tank and piranhas.