Minnow HELP

[West End Station]

We have two holding tanks for our minnows. One of them was painted a few years ago (never has any issues after painting) but lately we get minnows and they are dead by morning. The tank has plenty oxygen and is treated for the chlorine since its not well water. We do however let fresh tap water run into the tanks continuously. We do this for all four of our metal holding tanks 2 for minnows 2 for gold fish but this is the only tank that has fish dying in it. This is the only tank that we are having issues with. I am at a loss and about to stop using it completely. 

[DR.SPECKLER]

need to cycle tanks before adding fish,research fishless tank cycling.basically its getting colonies of good bacteria established in the filters to turn ammonia to nitrate,which is way less  toxic to fish..same thing happens in a new home fish tank.ammonia  build  up kills fish in days.

[buz23]

I don't think the ammonia cycle is killing the minnows, that's more of a longer term problem, not overnight, especially since you are probably not feeding the minnows.   I wonder if your tap water has too much chlorine.  Is that a stand pipe I see against the wall of the tank?  A continuous feed of water should work, unless it has too much chlorine.  Do you have some sort of good aerator too?  Are you careful to match the temperature of the tank to the temperature of the water that the minnows came in?  Mismatch in temp will kill them fast.

[West End Station]

We have a good oxygen supply with aerators. It just puzzles me because we have the same set up in tank two and the minnows do not die in there like they do in this tank.  I have noticed that some rust in showing through on the bottom of the tank where the paint is wearing off. Could this be related to the cause? We painted the tank a few years ago with pool paint.

[IceholeHEN]

you can buy cheap test strips to test the water and that should give you a little help on what is possibly wrong with the water. I personally would remove all the pool paint. when I worked on a fish farm we would always scrub the top 6 inches were the water hits almost every day. it got most of the scum cleaned up while aerating continued.

[HWeber]

Could this tank have a higher flow rate for the continuous flow of fresh water? Too much untreated chlorinated water getting in? With the flow through system its pretty odd theyre dying especially with all the aeration. Could you have some sort of cleaning product that soaked into your air stones?

[West End Station]

We do not use any chemicals when cleaning the tanks just scrub brushes and water. We do treat the water with Better Bait 24 hours prior to getting a new load of fish.

[West End Station]

Thank you for all of the help and suggestions I think we are going to move some goldfish to that tank and see how they do in it after we cycle the water. Maybe they will last longer. Fingers crossed!

[bshirtd]

might be a stupid question might not. Are the minnows in both tanks the same? If you have suckers in one and emeralds or buckeyes or any non hardy species in the other your bound to loose a few at night if you're holding a large amount of them.

[West End Station]

Yes they are the same minnows in both tanks. We will put 3-5 lbs in each tank so its not too many.

[DR.SPECKLER]

I would get a water test kit.test for nitrite,nitrate,ammonia,chlorine levels along with alkaline/acidity levels.test the water and find whats in it.hi ppm levels clog up gills too.somethings different..ive ran bait tanks for years and some of my bait died from old age.lol

[Gamalot]

Swap the aerator from the deadly tank over to the tank that does not kill the fish and see if they start dying. If they do then you have a bad aerator that is electrocuting your bait. I am not sure if metal holding tanks require being grounded but I would be looking into some sort of electro issue in that particular tank.

Some years back I had one of those battery operated aerators that floated and sprayed a mist over the top of my bucket. When I got to the water I found that device had flipped in transit and all the bait were electrocuted. It only takes a very minor electrical charge to kill bait fish.

Gam

[West End Station]

Thank you everyone! We still do not know what the issue is but we did move the minnows out of that tank and replace them with goldfish. They seem to be doing well in there. Thank you again for all of the input!