Mark on Foxface Rabbitfish - bite, disease, or something else? And what to do?

[yaksaredabomb]

Hi everyone,

I noticed a marking on the side of my Foxface Rabbitfish just today and it looks like it might be a bite. The middle of the fish's flat side seems like an odd place, though. Also, none of its fins appear torn or bitten and I'm just guessing but that's where I'd think evidence would show up first. Pictures are below, as best as I could capture them, along with a 100% crop of the marking.

This is a regular 75G tank with 20G sump, kept at about 78-80F. Plenty of flow, maybe even too much (3 propeller pumps in the display rated at 1200, 1050, and 750 GPH and a return pump in the sump estimated at 300 GPH). The fish don't seem to struggle in it, though - it's amazing how effortless their swimming appears.

The tank is fairly well established; the first fish were added about 18 months ago. The other fish are (in the order added to the tank) 2 clowns, 1 flameback angelfish, (the rabbitfish), 1 purple firefish, 1 starry blenny, 2 banggai cardinal fish, and 1 leopard wrasse. I think they all made it into the pictures.

There is this dark purple stuff all over that I think means I'm feeding too much and/or am not doing water changes enough. I'd rather not reduce their feeding so I've been trying to do water changes more frequently the past couple months to see if that helps. I've always used RODI and Instant Ocean. I'm not running any GFO, which I could consider too, but I will try to stay on the topic of the wounded fish for now.

So far all the fish seem to have gotten along well enough, though the angelfish and rabbitfish took a few days to get used to each other. All the fish seem to eat heartily too, everything from thawed mysis shrimp and "formula one" to NLS 1mm sinking pellets, cyclop-eeze wafer, and Julian Spring's SeaVeggies Mixed Seaweed Flakes. The only fish that won't eat any of the above are the cardinal fish - they have absolutely no interest in the 1mm pellets but I've seen them eat everything else.

Of all the fish, I think only the starry blenny has a mouth big enough to leave a mark like that. The blenny as seen in the last photo looks a little bigger than it really is due to perspective (it's right against the front glass and the rabbitfish is maybe 8" back), but it's not much smaller than it looks.

If it's not a bite, I wonder what it could be? Seems like an odd pattern for a scrape on a rock. If it's not an injury, could it be a disease? Even if it is an injury - I'm worried an infection or disease could follow. Other than the mark and being slightly less vibrant than usual, nothing else seems out of normal for the rabbitfish. It's still eating well and behaving as it always has - swimming around in the open, picking at the rocks, and occasionally "slurping" at the surface of the water and then diving with a splash and hiding behind a rock like it's embarrassed haha.

I have a 20G quarantine tank setup that I could easily transfer 20G of display tank water to as part of a water change. I am very skeptical/hesitant to use it, though, as the move could cause more stress than the wound. Also, I know the rabbitfish is venomous so I'd rather not risk being pricked if I don't have to.

I have a couple small hermit crabs of some sort and a few small snails. I also have hopes to upgrade my lighting and get an anemone and some of the "less difficult" corals someday, as well as 1-3 peppermint shrimp and 1-2 brittle or serpent sea stars. So I'm thinking treating the display tank is not an option.

Thanks for any and all input! The rabbitfish is one of our favorite so my wife and I are really hoping it pulls through!

(I wasn't sure whether this sub-forum was the best place for this thread or if "Reef Fishes" or "Fish Only & Aggressive Tanks" would be better. Please feel free to move it if it's in the wrong place - thanks!)

 

[Deinonych]

Looks like a bite to me. It's too perfectly rounded to be a scrape. Wouldn't surprise me if the blenny did it. Mine nipped a scale off my wrasse's forehead when the wrasse was getting too feisty.

Give it a few days and it will heal.

 

[yaksaredabomb]

Looks like a bite to me. It's too perfectly rounded to be a scrape. Wouldn't surprise me if the blenny did it. Mine nipped a scale off my wrasse's forehead when the wrasse was getting too feisty.

Give it a few days and it will heal.

Thanks Deinonych! I'll wait it out for now, then, and hope to see signs of the wound healing soon. I won't try to put the rabbitfish in a hospital tank or anything yet unless there's a change for the worse.

I'd heard lawnmower blennies can be quite aggressive so I was suspicious of the blenny right away for that reason too - but I thought starry blennies were supposed to be a little more friendly! Or at least I hoped the one I picked out would be. I suppose each fish is a little different.

Another thought, for later if it's needed, would be to leave the rabbitfish in the DT but pull the blenny out instead and put it in a QT/HT for some time - hopefully forcing the blenny to give up any territory it's staked out and make it settle in as the "new guy" once again in a few weeks.

 

[yaksaredabomb]

Well, in all likelihood the starry blenny has struck again!

The first mark was on the rabbitfish's right side, a little in front of the black spot. You can see in the first picture it looks like its healing - so that's great!

The new mark is on the fish's left side now, just at the bottom left of the black spot. You can see it clearly in the 2nd and 3rd pictures. It looks worse than the first mark I found.

Then, as I was wrapping up the photo shoot, I noticed a 3rd mark! This time again on the fish's right side, just in front of the black spot and near the dorsal fin. Right above the first mark I noticed. The blenny must have got him while I was looking at the photos on my camera or something as based on the first photo this 3rd mark definitely wasn't there just minutes earlier.

The rabbitfish is bigger than the blenny and doesn't seem intimidated. It swims right near the blenny seeming to not pay it any attention, even turning its back to the blenny as the blenny is perched above - looking like it's ready to strike. I fed some nori and the foxface, blenny, and flameback all went after it not really paying much attention to each other.

So it's not like the rabbitfish is all freaked out and hiding under a rock with its spines up all the time. And the first wound does seem to be healing rapidly. Both these charts one and two rate them as "Generally Compatible" or "Compatible". Maybe this is just a stage they're going through and they will work out their differences. But maybe not. Or maybe one of these times a wound will get infected.

I'm thinking maybe I should take the blenny out and put it on time out in QT for 2-4 weeks. Maybe that would "reset" the relationship and give the foxface a chance to get the upper hand.

Any opinions or other ideas? Thanks!

 

[yaksaredabomb]

Another pic of the prime suspect, maybe waiting to pounce:

 

[Deinonych]

Well, they do occupy the same ecological niche, being algae grazers, so maybe the blenny is being territorial. You could remove the blenny to QT (if you can catch him), but I would try to observe the behavior actually occurring before doing that.

 

[yaksaredabomb]

Well, they do occupy the same ecological niche, being algae grazers, so maybe the blenny is being territorial. You could remove the blenny to QT (if you can catch him), but I would try to observe the behavior actually occurring before doing that.

Thanks! Okay, I'll try to be patient a little longer. I'll also try feeding more nori the next few days. Neither of them looks like they're lacking for food but maybe if the blenny feels it has some competition the extra food will help it relax a little. At least enough to give the rabbitfish a break.

 

[Zalick]

Old thread, but chiming for future readers. I have the exact same round bite marks on my magnificent foxface. They look identical to the marks in the pictures above. I also have a lawnmower blenny. After reading this thread, I'm confident its blenny bites. Hopefully no big deal. The foxface doesn't seem to care. I've never seen it get bitten.