brown ridge on the belly?

[Mackenz]

Hi everyone! Last night I put some snails into MAckenzie's tank (my red-tailed puffer, Carinotetraodon irrubesco). This morning, I watched him when the lights came on in his aquarium. For a while he would just watch the snails, then he started attacking them. That was a relief because I was hoping he would eat them before they ate all the plants I carefully planted in there. Interestingly, a brown ridge would pop out just before some of his attacks. It runs from head to tail along the belly side of the body. Is this a sign of stress? I put about 5 snails in there....should I have just put 1 at a time? I will see if he does it again and try to get some pictures.

[Hilly]

Think of it as a threat display, the carinotetraodons can ridge the top and bottom of their body. I had never seen it until I saw my Salivator do it, it's quite impressive and amazing how quick they can raise and lower the ridge. Not a sign of stress.

[Myaj]

Yeah, thats just him trying to look extra big and tough, you know, showing those snails who's boss and all.

Its called a "keel" for future reference.