Angel fish keep dying

[cgronko]

Hey,
so i bought 150 angelfish about 2 weeks ago and put them all in a 55 gallon tank and have been selling them. There are about 100 left in the tank which is a bare bottom tank and has just a sponge filter and an aerator in it(its a bare bottom tank). Everyday there seems to be one or two fish that get sick and end up dying. The water temp is around 80 degrees. I feed them about 3 times a day. These fish are from nickel to quarter size. I do from 25%-50% water changes almost every day and the water parameters are perfect(0 ammonia 0 nitrite, 0 nitrate). I have fairly hard water but so did the person that i got them from. I cant figure out why they are dying. Any suggestions to make this stop? Should i add salt or raise the temp? Any suggestions will greatly help! Thank you!

[Ryuu]

Sorry to hear, I have one question though, when you mean you sell them, you mean your like a private breeder? and I dont want to be nosy, but is a good way to make money?

[Algenco]

thats not uncommon, I'll lose 1-2 "Runts" per day for awhile

[cgronko]

These dont seem to be runts though. Some of these fish are the bigger fish in the tank.

[Lady Hobbs]

You may have to increase those water changes. Have you been testing for ammonia and nitrite levels? Could be that small sponge filter is not enough for larger fry now.

[cgronko]

Hey,
The water parameters are perfect. 0 ammonia, 0 nitrite, 0 nitrate. Is there such thing as too many water changes? Well the weird part about it is that all the fish that are dying are from one supplier. There are also about 30 fish i got from another supplier in the same tank and not one of them has died. These fish that are dying dont seem to have anything physically wrong with them. They are all good size. I cant figure out what it could be but i am getting about 3-4 died a day now.