I have a 120 gallon fresh water tank with a course grade Aragonite Sand and lots of large reef rocks and lava rocks. The filter is the large Flugal cylinder canister with 4 tiers in it. My aquarium has been established for 1.5 years where it is, and has been with me in this configuration for 5 years at 2 different locations. My fish were: 1 two month old medium sized (about 6 inches)Frontosa, 1 six month old Bumble Bee (6 inches) 1 one and a half year old Electric Yellow (4 inches) 1 six month old red zebra (4 inches) 1 one and a half year old Girraffe Hap (8 inches), a 3 year old Cobalt Blue (6 inches), A 6 month old pencil fish (7 inches), 2 three year old Pleco’s One black, One gold , A two year old clown loacher (3 inches), 2 three year old Birchirs, I also had one large South American cichlid that was 2 years old and about 9 inches.
A week ago I added a Borleyis (3 inches). It seemed to be gasping for air after the first day of being in the tank. It wasn’t picked on by the other fish and it maintained itself pretty well. It kept gasping though and that worried me. I checked my water levels again and everything was where it should be: Amonia 0, Nitrite 0, Nitrate about 40ppm, Ph 7.6 (I know its low, but thats where it’s usually at and the tank has done well with it there for 5 years now without a problem) I had cleaned the filter 2 weeks prior so it wasn’t that, the thermostat keeps the tank at 25 celsius. I added 2 tablespoons of Amquel+ and NovaAqua+ water conditioner to see if it would help the little guy aclimate. 4 days later he was still gasping. None of the other fish show any signs of distress. Eating normally and no rubbing, scraping, aggression, or gasping behavior. 6 days later he’s still gasping so I ran another water test, same results. I left to run some errands and came back 2 hours later. All of the fish in the tank were at the surface gulping air! My temp was fine, my chemistry was fine, the bubblers were running strong, the filter was flowing strong. I didn’t know what to do. Then 2 of the fish dropped to the bottom on their backs gasping. I lifted them up in an isolation pen and put it the flow of the filter outlet to keep water flowing over their gills. They were dead in an hour, and 3 more had dropped to the bottom, including the New fish. I left them down there since putting them in the filter wash didn’t help the others. They were dead in half an hour. I put the 5 fish in bags, and did a 10 gallon water change. The other fish were still gasping at the surface. I grabbed a water sample and the 5 dead fish and went to the fish store. The guy there ran a test and said my PH was way too low and that was what killed them. He told me my substrate was wrong and it wasn’t buffering the PH. I’ve had that substrate for 5 years with no problems. The fish in my tank have never done this before, and it all happened at once. I asked if the new fish could have contaminated the tank, and he said no. He told me that they had the Borleyis and it’s tank-mates for quite some time and never had a problem. I got a call from my room mate and 4 more fish had died while I was at the fish store. I asked what I could do, and he told me to change my substrate and increase my PH. I went home and my Clown loach was dead now too.
Now I’m down to my 2 birchirs, and my 2 plecos. I know th e issue wasn’t the PH level. These fish have been fine at that level for 5 years. This location, the tank has been set up and running for 1.5 years. I don’t know what would cause this to happen to all of the fish all at once other than a disease. I don’t want to change my substrate, change the water, and put new fish in there to get sick. If you don’t think it’s disease related, what is the fix. If you do think it’s disease related, what do I do to detox the tank and the 4 contaminated fish I have left
One of the Plecos was dead this morning, so it apparently is effecting the bottom feeders as well. The Plecos don’t require a high PH so Now I’m positive the PH is not the culprit. The South American Cichlid I’ve had for 2 years with the African Cichlids. He’s Huge and very docile. I wouldn’t normally mix the two and don’t recommend it, mine is just a giant freindly anomoly. Birchirs are a type of lung fish and may not be as adversely effected by a problem the other fish may be experiencing… it appears to have been suffocation. The surviving Pleco shows no sign of distress, nor do the 2 Birchirs. Thanks for everyones help! I’ll try some of those websites.
PH of the water is 7.6. There hasn’t been anything introduced into the tank other than the new fish. Thanks for the great answers. I wish my rank was high enough to give you guys some thumbs up ratings.