My Demasoni are all dead

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AC Members
Jul 18, 2010
I bought a new 55 gallon Tank and set it up. I know how to set up a tank because I have 40 tanks. It was now ready for fish so I put in 15 or so Demasoni Cichilids. About a week later I checked all the parameters and everything was good. The temperature is about 79 - 80 degrees and I have two large sponge filters in it plus a heater. Three weeks later all15 Demasoni were slowly dying. I checked the fish and they had nothing wrong with them. I had three other tanks of Demasoni and they are fine. By the way I have two Plecos in there that are still alive. Now I have a empty tank which needed to be scrubbed and new filters. I also put in the tank some salt and declor. Now my tank is ready for more fish. I put another 15 Demasoni in the tank, and about two weeks later all 15 slowly died. I still have the plecos and I put in two guppies which are living. I also changed the filters I now have a large water fall filter at one end and a large sponge filter at the other end.
Could it be to small a filter and to high a temp meaning not enough oxygen? The fish were not breathing heavy or acting strange in any way. What am I doing wrong I have never had this happen before.


Eheim User
Feb 9, 2005
Medina, Ohio
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Bonnie, I am so sorry for your losses!

Either the fish were sick from the vendor, there were too many of too large of fish for the bio-load or they killed each other off.

I'm guessing from your comment that you have 40 tanks worth of experience though water parameters may still be an issue. Can you post your water test results?

It is also possible that oxygen levels and higher temps may be a contributing factor. I keep my tanks cooler, usually under 78F without problems with growth or breeding.

How large were the demasoni?

Do you also have more Malawi cichlids in your other tanks? Just asking, I haven't checked your other posts.


Josh Holloway--Be mine!!!
Sep 1, 2003
Calif. SF Bay area
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It could be the acclimation too. What are your water parameters?


AC Members
Nov 7, 2018
San Juan, PR
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I was not lucky with Demasoni. I had other mbunas before and then, I decided to put 14 demasoni in a 55 gal tank with a nice amount of rockwork. They started to kill each other and after 3 weeks, there were 3 of them left. I still have that tank with only those 3 " demonsoni " (that is what they are, really!).