Bug-eyed Bass

[Phil Lilley]

There was a question about the bass, and may be other fish, in Bass Pro's aquariums. I believe also the tanks in question are located in Springfield, although other shops may have the same issues.

The question was what causes fish's eyes to bug out. I enquired and got the following answer from MDC fisheries pathologiest Devona Weirich, DVM

The answer to your question is: yes, one of the most common causes of pop-eye is nitrogen supersaturation of water. This is common in water sources that are spring or well fed as well as below dams where gases are compressed due to falling water. In these instances, along with bulging eyes you may see pockets of gas under the skin or in gill tissue. Now the other very common cause of pop-eye is a bacterial infection. With these you may also see a reddened fin base, a distended abdomen, or frayed fins. If you cut the fish open you may also see fluid in the abdomen or other hemorrages on internal organs. It is best diagnosed by a bacterial culture. Determining the cause of pop-eye is sometimes not easy. I have taken bacterial and tissue samples from aquarium fish with pop-eye and found neither a parasite, bacterial infection nor gas supersaturation. My conclusion at that point was that the tissues around the eye were permanently damaged by some prior event that is now undetectable. If the fish are eating well and do not show external signs of disease, this may be the most likely situation.

[Chief Grey Bear]

Thanks for looking into that Phil. I figured there was more to it than for catching prey. I did think though that the magnified glass played a roll in it.

[Trav]

Interesting

[taxidermist]

Thanks Phil! Every large aquarium I have been to has this, to include Sea World Cabelas and the ones overseas in Berlin and Spain. Also a friend has lots of photos of wild fish from a fellow in Minn. ( I think) and the wild fish show it too. maybe not so badly bt they do show it. So it may be just from eating well. When fish are removed from the water they dont show it or not as well.

I tried for years to photo them underwater in the lakes but wild fish are really hard to take good photos of with normal scuba gear. You almost have to have a rebreather. I have a freind that libes in Cozamel, She does a lot of underwater video for dive trips and even the Marine fish show it and many times much worse.

We have speared Red Ssnapper and other fish in deep water and ther eye will popout of when brought to the surface but thats from really deep water.

Thanks for the info Phil.

John

Yep I certainly can believe in many cases it from physiological disorder too.

[DoctaJ]

I can't speak for all aquariums, but the BPS in St. Charles, I don't think they get fed enough. Fish feedings are only on Sat and Sunday at 2. I will say that they have started dropping pelets in on Wednesday. However on Sat and Sun, they don't put many minnows in the tank. Anytime we lose a fish, it has to be frozen and sent off for an autotopsy.

[Chief Grey Bear]

I went to BP Sunday and made a trip by the tank. Out of all the of the fish in there only 3 Largmouth Bass and 3 Stripers , had bug eyes. One of the stripers eyes looked to be just about completely out of the sockets. But all of the others, even from the same species, looked just fine.

Maybe these were new to the tank and had not adjusted yet. Beats me.