Shiners with discoloration and fin problems

I just got my bait tank all set up and have been having good luck until my last 2 lbs of shiners I put in there. My tank is a 100 gallon plastic stock tank and I have a large aerator good for 180 gallon tank with 4 stones running in it as well as a 550 GPH pond pump with an external pond filter good for an 800 gallon pond. The return out of the filter runs into a 28 inch piece of 3/4 PVC with many many holes drilled in it to spray water down into the water. Water normally stays at 75-80 degrees in the garage.

My problem here recently is a lot of the shiners look discolored when I look at them in the tank. They have large areas of white on their backs as opposed to the normal black coloring. When I dip these shiners up and look at them they are missing all of their scales and it looks like something has been eating at them. Some of them are missing most of their tail fin or missing parts of their mouth/lower jaw.

What in the world would this be? I assume it is some sort of fungus? I will be taking all of these shiners out of this tank tomorrow but I dont want this to happen again.

Your tank is overcrowded and you have a fungus that will continue to kill your minnows. You have too much aeration and too much turbulence in the tank which is causing stress on your shiners. You need to add around 4 ounces of rock salt and 2 tablespoons of oxytetracycline,which is available at your local coop, to the tank. The antibiotic will kill the fungus and the rock salt will promote the slime layer. At best, the tank should only hold 1 pound of minnows and the minnows need to be fed.

I'm just guessing here, but isn't 75-80deg a bit warm for Shiners ??

... cp :cool:

Shiners can take the heat, but it would be better if the water was cooler.

I would clean and disinfect the tank before getting more minnows. Wash real good afterwards cause disinfectant could kill them.

Sounds like you got em alittle over crowded, expecally if their tails look short

Way too warm and way too crowded. Definitely fungus is killing your bait. Overcrowded and less than perfectly maintained home aquariums have the identical same problem with fungus. Your set up is perfect for such an infection. Oxytetracycline and non-iodized salt may work as a temporary stop gap, but it may already be too late for most of those you already have. It really pays to use the oxytetracycline immediately on each new batch, too, they will be coming into your operations heavily stressed already. And before you use your salt, be sure that the species you get is salt tolerant, not all of them are. Your source of supply should know about the salt tolerance and the proper dosage for the oxytetracycline.

Best to tear it down, scrub it down and start over. Do not use soap or detergent to clean it with either. Actually the best disinfectant is vinegar, because after a real good washing what residue is left in the tank walls should be eliminated or at least rendered harmless, if you let the operation run without fish in it until the nitrate/nitrite cycle works itself out. Normally that cycle only needs to be worked out in the beginning. Soap and a lot of other disinfectants soak into even glass leaving behind a very persistent residue that will kill fish.

If you are getting scum and foam on the surface you may also need a protein skimmer and you definitely need to be a whole lot faster to remove deads and dying.

There are coolers available at little or no more cost than the big aerator that can be used to keep your tank temperature down, too. The aerator is probably overkill anyway, like was mentioned in another response. A whole lot of bait shops even up here north in Minnesota use them. If you are handy, you might even be able to make your own out of an old refrigerator that is still working well. You wouldn't have to set it very cold either. Local shiners can take the heat well enough, if everything else is perfect, but cooling them off makes keeping them a whole lot easier. If you feed them, also be sure to siphon off what they don't eat up right away as well as any accumulating waste products. Sanitation is your friend.

If you got a Scheels in your area that has a minnow tank, ask to see their operation, including the back room. One of my cousins got tired of cleaning scum and tossing out massive deads in their Sioux Falls operation and designed a set up for them that very effectively dealt with that problem. He has installed that setup for them quite successfully in a number of other Scheels stores around the country.

I assume you are referring to a bio filter?

A bio filter works on a balanced nitrogen (nitrate/nitrite) cycle generally centered around some sort of sponge or something like one that holds an active bacterial colony serving a relatively stable tank with a long term population, a protein skimmer actually removes organics before they get into and possibly overwhelm that cycle. In a hobby situation you see protein skimmers more often used in marine aquariums, since the balance there is often quite a bit touchier and the sizes are generally much larger, but they are not restricted to marine use.

Thank you all for the replies! I would have responded sooner but we are spending 10 days at the lake fishing for crappie and walleye and this is the first time I have been anywhere with internet access.

I will certainly start from scratch again and keep the number of shiners down so I am not over crowding them.
Does anyone have a link or know of where I can pick up one of the coolers you were referring to?

Thanks again for all the help! It is much appreciated.