Tropical Fish Hobbyist

Rabbitfish
in Trouble

I’m afraid I’ve made a serious error in judgment. I recently foxface rabbitfish that looked perfectly healthy—no white spots, damaged fins, or anything else unusual—and was eating well at the fish store. I took my chances and introduced the fish to my 75-gallon FOWLR ( fish-only-with-live-rock) tank without quarantining it first—I know, typical rookie mistake! Now it is constantly scraping itself against the rocks, twitching its body, and generally acting nervous. It also seems to be breathing much faster than it should.

water because carbonates make up the majority of the buffers in salt water. The practice of calling a basic pH “alkaline” is especially misleading because it is possible to have a high pH and low alkalinity. When this condition exists, pH is unstable and can plummet rapidly when acids (in the form of decomposing fish waste, uneaten food, etc.) are introduced. I hope this clears up that confusing terminology a bit!

Q

Iggy Tavares

The foxface rabbitfish Siganus vulpinus, seen here in stress coloration.

I assume it has a parasite of some kind, but I’m not seeing any white spots. I realize that I’ve just learned a lesson the hard way, but is there anything I can do to help

What you’ll need to do now is capture the rabbitfish (be careful of those venomous spines!) and move it to a separate hospital tank. Before transferring the fish, I would recommend giving it a 5-minute freshwater the fish? Will all my other fish become infected, too?

Mark Bingham

Mobile, Alabama

A

Don’t beat yourself up too badly over this. As you’ve discovered, bad things can happen when we fail to new specimens. Many of us have made this classic blunder at one time or another in our fishkeeping career, but it only takes one bad experience to turn the lackadaisical aquarist into a die-hard proponent of quarantining.

quarantine

You’re probably right that your rabbitfish is infected with some form of parasite, several types of which are known to afflict marine fishes. Cryptocaryon irritans (saltwater ich) and Amyloodinium ocellatum (marine velvet) will cause the symptoms you’ve described: scraping, twitching, rapid respiration, etc. If one of these parasites is the problem, you’ll eventually see white specks (in the case of Cryptocaryon) or velvety or powdery patches (in the case of Amyloodinium) on the fish’s body. In the early stages, however, you may not see any external symptoms apart from nervous, irritated behavior.