5 C. frontosa dead in a snap, any ideas


Howdy all,

I just came home this evening and as I was getting ready to feed 5 C. frontosa, that I had just seen yesterday and were behaving fine, that they had Popeye.

I've never dealt with this problem before but all but one seemed to be affected.

After 2 hours of research all were upside down and floating on the bottom, not yet on the top.

I will test the water tomorrow, after the fish themselves are gone.

Just haven't ever experienced something that was so lethal so quickly. I was hoping to get Kanamycin tomorrow but no time to do it.

When it rains, it pours.


Staff member
Wow, very weird to hear of something occurring so quickly! It sounds like something poisonous in the water. Did you do a recent water change or around any chemicals that could have gotten into the tank? Chlorine poisoning, or something dying in the tank would be my first guess. Significant changes in pH can make the ammonia and nitrogen cycle deadly, especially to African cichlids. Sometimes the water company adds chemicals to treat the pipes and neglect to tell us. Guess they don't won't us to freak out by extra doses of mystery chemicals that won't kill us but fish, well that is another story!

Often it is just the water chemistry just reaches a tipping point and when one fish dies their body pollutes the entire tank. The fact that your fish had popeye, sounds like a bacterial issue. Probably a healthy water change would help. Does the water smell bad or are their any bubbles on the side of the tank? Any recent changes in adding décor, new food or a water change?


Thanks for the words.

I had the water tested just to take my bias out of it and no measurable Nitrogen of any kind. Nitrate, -trite, or ammonia. pH stays a steady 8.2-8.4. Water had not been changed recently but I did just pull the pumps on the filters and clean the impellers, like I do from time to time, but that was several days before incident. But no chemicals or anything introduced anyways.

This was a 24 hour killer.

Very big popeye pushing the eyes forward, not just overall swelling. Not cloudy. No way they all injured themselves at the same time.

The only thing that I can think of is that I pulled their 200w heater to put in the 55, which I finally got all cleaned and ready. I replaced it with a smaller 100w that I'm thinking now the thermostat may be fouled on. Either way, it's just LO-HI, not clear degrees like the Eheim that I pulled. So I just guessed at where it should be, usually 82 F.

After I found them the water felt warm, but not crazy warm. I couldn't see the thermometer with a little algae on it, but the tank was running a few degrees hot for sure. Maybe 90 or so, even. But I didn't think that temperature symptoms would look like that. Maybe it's a reach.

I still don't know and I was getting ready to put them in the 55 this weekend, but not now. The bull male had a nice cephalic hump and stretched tip to tail from my ring finger tip to my wrist.

I sure would like to find a few more to work on the plan that I started but not until I figure this mysterious killer out.

They were eating and were vigorous one day, then less than 24 hours later, adios Frontosa.


They were the only fish in the tank also. No other fish to die and foul the tank or anything like that.

They were all in, then all out.

But no survivors means there's no way to recreate the conditions if one were to do such a thing.

Not with C. frontosa anyways.

I wonder about the effect of temperature on Africans, more generally.

If a heater goes out you better have a back up for sure, but what is the upper limit should a system go off the rails that way?

Not sure if I've seen much about high temps and Cichlids. Some aquatics and Amazonian, but not Africans specifically.


So now I have to experiment, being just the man that I am. In the name of Sir Isaac Newton, we must press forward.

I didn't break down the tank or change the water. Didn't have time to before the frontosa went upside down.

But since everything is still running, I have to know will this tank do this to another fish? Or is there something to learn? Must study the wreckage.

So I popped in and bought a little yellow lab for like $4.

The tank is the control. It has not changed other than a little water top-off. Less than 1 gal total. Same same same.

The fish is the variable. He/she is new to the environment but had to be an African just to more greatly eliminate the chances of something weird happening because the water conditions (No measurable Nitrogen, pH 8.3, GH is very high and CaCo3 is in the tank, Filtration is by 2 Aqua-Clear 50s turned down to low b/c the tank is a 29 breeder and too much agitation) I have the 55 that they were going into finally up and ready with an Aqua-Clear 110, but killed these first.

So if anyone knows C. frontosa breeders, please send them my way. I wanted that initial colony of 5 or 6 and then add selected Tangs and cats or loaches and let them be happy. An A. compressiceps "Calvus" has seemed an interesting fish, especially with gold or sulphur heads. I would love to have 1 Tropheus, as long as I can just get one with nice coloration. They eat completely separately from either of the other 2 pescatarians, but can keep a tank in line like a queen be. Maybe a few loaches or even siamese algae eaters that are larger can tolerate the conditions if you acclimate them. I tend to not like plecos in African tanks, but you know, you've got to find what works.

So what works is....... Does anybody have a lead on5-6 pre-adult but not far away C. frontosa. More blue is more better and a couple males and 4 females is the bestest, but how might you know that just yet, other than cephalic hump and behavior, but you can have a Bull Female. I'm in deep at this point.

That was my vision and bam!!, in one night just a few nights ago, the months of work that I had put into these guys just dissappeared.

I don't think it was the water. I think the thermostat broke and heated the water to much.

We're about to find out.


Experiment concluded. Enough data recorded.

When I came in the evening, which was a bit later, just like last time the troop was not looking good. Sunk to the bottom. Large, not quite bulging eyes but large and distressed. Little movement.

Other tank is happy lovely.

Check the thermometer and it was just over 90F. Holey Moley. Not being able to see well, I misread the dial and didn't figure out where to put the knob. On a 300w heater in a 29gal breeder.

Might get hot kind of fast. Plus I don't think the thermostat works well. It comes on at odd times, but with so little overrun in the tank, it just goes up and up.

I wish I had just left well enough alone.

So water change 5 gal on the yellow lab in the 29 gal tank but much cooler and turn the heater off. Already seems better.

I will try food.

My conclusion so far would be that C. frontosa are just a bit more sensitive to high temperature swings in the tank. From 82F to 90F because of a mistake killed mine in a day. I believe other mbuna to be more robust to temperature variations.

n=1 mbuna now + ( a whole ton in the past)
n=6 frontosa
Very Interesting. Sorry you had to lose your fish because of a heater. That makes sense as Frontosa's are a deep water fish where the temperatures would be stable and lower. I am keeping a deep water hap, star Sapphires, but I don't have any heaters in my tanks (I have a heated fish room) I think you are right in high temperatures. My water temperature varies quite often, but never that high. I will be watching my fish for stress to high temperatures. I was like Mikey in suspecting water quality. The KC Water department adds extra chemicals due to water levels and conditions in the Missouri river all the time. I think you figured out what went on and it should be a lesson for us all to be observant and try to figure what went wrong when we lose fish.


New member
I would say you probably figured it out. I prefer to keep the temp around 80 give or take with my Africans. Not many fish I’ve found thrive at 90.


New member
Thank you for posting it here, now we know that 90 is not good for this fish. I'm really sorry for your loss.