[ozzkoz]

I've had a 75 gallon cichlid tank (yellow lab and maingano) for 10+ years and my fish have slowly been dying off over the past 2 years. I'm guessing they are getting up in age and then went below a critical threashold where aggression is starting to pick them off one by one.

Reason for post, I'm down to 3 labs and 4 maiganos, looking to purchase juveniles to re-stock my tank. Will adding ~20 juveniles to my existing 75 gallon going to overwhelm my bio filter? I'm running an ehiem 2215 canister and penguin 400 HOB.

Could I add yellow tail aces to the mix? My kids love purple. Was thinking maybe a total of 8 to 9 labs, acei, and 10 mainganos. If not I'd target about 14 labs and 10 mainganos.

Thanks

 

[DJRansome]

I would add one group at a time. Eventually 1m:7f maingano and 1m:5f labs and acei. Shoot for 20 individuals in the end. Know that acei are not truly purple unless you think that periwinkle is purple. They can look periwinkle or blue depending on the way the light hits them at any particular moment.

Average life span is 8 years so it may be simple old age.

Since the ratio is most important for the maingano I would add them first. Do you know whether your current maingano are male or female? You will likely need to add a large number of unsexed maingano and need to rehome some males as you will likely get too many males in the process of trying to get 7 females.

 

[jcover]

Something I would be slightly concerned about is the potential for "Old Tank Syndrome" as well, since this has been a well established set up for quiet some time.

 

[DJRansome]

It is assumed that tanks have 50% water changes weekly and nitrates at about 10ppm when adding fish.

If your nitrates are high...do small (start out with 20%) weekly water changes for a number of weeks to get the tank healthy for adding new fish.