Ancistrus that keep dying?

[kegro144]

Hey everyone!
I’m new to the forums but not to ancistrus species plecos. Now I need some experienced advice….
I have a 150 gallon tank that is being used as a albino/common breeder tank along with various other ancistrus types grow out tank. This tank has been set up and used for 6+ months.
Starting last 7 days ago, I’ve been losing fish just about everyday. They start with red spots in various places on the body and then over the course of 48 hours they are bloated and gone. For the most part it’s started with the biggest plecos and slowly been going down to smaller sized plecos. It’s also mostly been albino females which I thought was weird. Water parameters are in check with the following data (ammonia-0, nitrite-0, nitrate-80 (higher than ideal I know) pH-6.. Diet hasn’t changed in 6+ months, I feed green beans (fancy cut no salt added) along with northfin veggie pellets. Current treatment has been metroplex and Kanaplex with the addition of paraguard and prazipro three days ago and a 2/3 water change yesterday.
In other words, I’m at a loss of what to do?
Pics will be attached and questions/clarifications are welcome.

[fishguy1978]

You need to do some heavy water changes and clean filters. You also need to move stuff around in the tank to get all that peco poo syphoned out. Once the nitrates are down to safer levels you can start medical treatment.

[bekateen]

I agree with fishguy1978. Big water changes, clear build up from your filters, and siphon gravel/sand. If your substrate is more than 1/2" deep, consider removing fish from tank before disturbing the substrate, because it might release toxic gasses.

Once you do this, you may not need medication.

Good luck,
Eric