A problem with my engineer goby's skin

[onyzza]

My engineer goby's developed two bumps behind its head, pretty much on the back near the pectoflake fins. The bumps are fairly round and aren't raw or discolored, just...there. Tank stats are still the same: 0 on NH4/NO2, NO3's near zero now thanks to the mcora, pH's 8.2-8.4, and sg's around 1.025. I thought maybe the bumps were from a growth spurt - the goby's gotten a bit too wide for a favorite hole in the rocks and I've seen it stuck there more than once in the past week. But then I remembered I introduced some new mcora a few weeks ago, which is the only change I've made to the tank. I washed and scrubbed the mcora in clean saltwater before adding it, so I'm thinking it's unlikely I brought in anything bad. Still, I'm wondering if I should be worried these bumps are more than just bruises from squeezing between rocks.

[fleeton]

Those bumps can be tough to figure out. Could be bruising from squeezing through tight spaces, or maybe something else entirely. I've heard of fish getting tumors, although it's pretty rare. Wish I could offer more insight, but I'm stumped. Got any pictures of the bumps you could share?

[onyzza]

Thanks for the input, Fleeton. I appreciate your honesty about the difficulty in diagnosing the bumps. I'll definitely try to get some pictures of my goby, although I'm expecting it to be a challenge. As soon as I approach the tank, the goby darts under a rock or starts frantically searching for a hiding spot.

[onyzza]

Ugh, getting clear pics is a nightmare. I managed to snag a shot from the top after using the magnet to distract him with the camera out of sight. The good news is that one bump has vanished and the other has shrunk a bit, although it's still there. For what it's worth:









(I'm not sure circling something that's barely visible will make a huge difference, but )

Since one bump has disappeared, I'm hoping the other will follow suit eventually.

[fleeton]

Tough shot indeed. Not much more I can add, but glad to hear the bumps are fading.

[onyzza]

The bump on the back is still there, although somewhat smaller, but now my engineer goby has managed to acquire a brand new lump on the top of its head. I'm stumped as to how it's getting these...I'm starting to wonder if I need to reposition some of the rocks or something. The smaller rocks can shift a bit, but I don't think they're in a position to fall or cause anything else to fall. The goby's behavior has changed a bit too - it's still eating just fine, but it's suddenly not a fan of going under rocks. In the last few days, it's also started this weird thing where it's rubbing its head all over my sea hare. I figure there's probably a connection between not wanting to go under rocks and having a bump on the top of the head, but I just can't see how a rock could have caused this one. Could there be something to the fact that it's only doing this with the sea hare? The goby isn't scratching or rubbing itself on anything else in the tank that I've seen.

[felinxo]

That's really interesting about cancer tumours, Ski. I recall reading that sea hares produce a poison which is being researched for its potential use in treating certain cancers - I wonder if the fish has somehow intuitively picked up on this. If so, that's just incredible.

[onyzza]

I'm starting to think the sea hare's slime might be the reason behind the goby's behavior. I've handled a lot of gastropods, and sea hare slime is definitely thicker than most. I've been trying to find some info on what's in it, but so far no luck. The thing is, the goby's only doing this with the sea hare, not the other gastropods in the tank. And the sea hare just seems to be going about its business, like nothing's wrong.

The big bump on the head is getting smaller, at least - it's less than half the size it was before. The one on the back is still the same, though. I'm keeping my fingers crossed that it'll go away and no more will show up.

I'm also wondering if the urchin might have something to do with the bumps. I've had it in the tank for a while, and it's always been fine, but since I lowered the temperature from 78-80 to 72, it's had a huge growth spurt. It's almost twice the size it used to be. I've never had any issues with it before, except for the occasional nip on my hand. But now I'm starting to think that maybe it's been nipping at the goby, too. They do share caves in the rock, after all. It's really frustrating that I still can't figure out what's causing these bumps.