Tropical Fish Forums

[Aquaman87]

My blue tang has started hovering around the top of the tank whee the filter creates a current. Is this for food, more oxygen, or what? This is my first tang and my neighbor gave me a fully grown blue tang that was too aggressive for his tank. My clown and blenny seem fine. I changed my filters and my water tests are optimal. Filtration should not be an issue as all equipment came from my neighbor's 100 gallon tank to my 20 gallon. He upgraded to a 300 gallon and I want to increase size as I gain experience. Also, can tangs jump out of a tank? My neighbor suggested hanging my reef lights 9-12" above the tank. I have a clear plastic cover on it now to reduce evaporation. Each night then tank will bang against the plastic lid while racing around and jumping. Amusing but I often wonder if he's suicidal!

[FloridaBoy]

Is the fish doing this continuously? Assuming we are talking about Paracanthurus hepatus; they do act crazy sometimes; for example they will usually exhibit "nesting," whereby they pick out a coral crevice or hole in the rocks, and it's not unusual for them to retreat into it and just sit there during the day. Other strange behavior can include random scratching and even lying on their side for no apparent reason!

However, a continuous demonstration of the type of behavior you are describing (constant surface hovering, trying to jump out at night) is NOT normal. It's difficult to say from here, but it almost sounds like the fish was possibly injured or maybe being bullied or threatened in some way. Some pathogens like Brooklynella and Amyloodinium (Velvet) can result in this behavior, both of these pathogens attack the gills first, and induce an increased respiration rate; in both cases the fish can eventually be found gasping for air near the surface. In this case your other fish would also be attacked eventually.

If it were me, this fish would be observed carefully for any signs of pathogens or illness until it hopefully recovers. If it starts to decline, it can be moved to a quarantine/hospital tank. Be advised; these are notoriously susceptible to attacks from Cryptocaryon irritans.

As for covers; yes
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[Aquaman87]

Thanks! The tang I have is 3" long and fully grown. There's one particular spot where he spends time at the top of the tank. It looks as if he is feeding rather than gulping for air. My lid is not tightly sealed, just covers enough to support an older, basic light and keep the tang from jumping out. He seems fine. Eats well, color is good, eight is fine. Fun to watch. A bit of random scratching on one side against a shell but it doesn't slow him down. He can't be bullied as he is the largest by far. I only have him, the clown, and a blennie. I wonder if he feels most comfortable there because the water movement is strongest. He stayed in my neighbor's tank for several months or more and he has currents set for 40' of natural Pacific reef. My neighbor has is a saltwater aquarium consultant. I'll keep observing the tang for signs of distress.

[Osprey]

Your tang is most likely bored. Tangs in too-small tanks will sometimes display behavior like that- they are fast swimmers and require a lot of room to exercise. More often they swim directly in front of the strongest powerhead in the tank, but the current from a filter is a likely substitute.

If your tang is a blue/hippo/regal tang, you are mistaken about the adult size of the fish... I have a specimen that is six inches long and still growing.
http://www.aquahobby.com/marine/e_hepatus.php
^Is this the fish in question?


I really wouldn't recommend tangs of any species in a tank smaller than 75 gallons. Eventually they'll get too big, and you'll have to catch them to relocate them. I've observed the process, it doesn't look particularly pleasant.
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