If you read my other first thread, i just got a F8 puffer, and it creates alota mess while it eats...i baught a small crab about 1" or 1.2' (pic below)
It should eat anything off the floor, my question was will this do any harm to the f8? will the f8 eat it? or should i just feed it to the piranha i have
Do you know if it is a tropical crab? If it's coldwater it won't last long. Anyway, the point is moot as, yes, the puffer will likely eat it. And make a great old mess in the process.
PLEASE test for ammonia, nitrites and nitrates. Most likely, your tank is not cycled. Your main priority should be keeping the tank *as clean as possible*... this means minimal to no food and regular water changes.