Seeking Help...

[FishGuy456]

Good day fella's, I have a problem and I am hoping some of you knowledgable fish hobbyist can assist. I've had several fish past away within the last week (7) in total. = 5 African Cichlids Mbuna type, 1 Rainbow shark, 1 Giant Danio....

Here are my water parameters which was tested on May 4, 2021. . 55 Gallon tank. One HOB filter as well as a sponge filter in tank.
Temperature 84 Degrees
Ammonia- 0
Nitrites- 0
Nitrate- 0

Because the Nitrates were so high, I did a partial 25% water change. On April 23, my water parameters were-
Temperature 84 Degrees.
Ammonia- 0
Nitrites-0
Nitrates-40.

My Rainbow shark at the time was lethargic so I moved him to the Quarantine tank.
My Dolphin cichlids (2) didn't make it.

I can't figure out what the issue is and as you can see from the very top, all of the water parameters are within specs, or very much close to.

Any and all assistance is truly appreciated.

 

[Wyomingite]

Unless you did a near 100% water change immediately before testing, your nitrates shouldn't be 0. You should have some reading simply because of the nature of the nitrification cycle. Nitrates are the end result of the process. I'd check the expiration date on the test kit and make sure the test is accurate.

The dolphins (Cyrtocara moorii) typically reach 8" TL; I've seen them as large as 10". BTW, dolphin cichlids are haps, not mbuna. Rainbow sharks can push 6" and giant danios range from 3.5" to 5" depending on which species you get. I've seen at least three species sold as giant danios: Devario aeguipinnatus, Devario malabaricus and Devario assamensis.

So questions:

What were the other cichlids in your tank?
How large are they?
How were the dolphins acting?
How is your tank aquascaped?

The shark and the cichlids occupy the same basic area in the tank and occupy nearly the same niche in the food web, so they're competitors. Depending on the other speccies of cichlids, I'm wondering if there isn't a fair bit of competitive stress causing your fish to become ill. A 55 gallon tank is a little small for some cichlids.

WYite

 

[FJB]

I would also suggest stating what is the frequency and volume of water changes you use.
It does sound as if your test kit may be giving inconsistent results. It may be expired. I would also run duplicate vials and make sure to shake the solutions a lot, and to pre-rinse well the test vials. If strips are being used, they also go bad, are generally less accurate. Regardless, 40ppm nitrate before or after a water change is too high for good health.

 

[Wyomingite]

I would also suggest stating what is the frequency and volume of water changes you use.
It does sound as if your test kit may be giving inconsistent results. It may be expired. I would also run duplicate vials and make sure to shake the solutions a lot, and to pre-rinse well the test vials. If strips are being used, they also go bad, are generally less accurate. Regardless, 40ppm nitrate before or after a water change is too high for good health.

Thanks, FJB. I started going down that road with the break down on the size of the fish and got side-tracked with the potential aggression.

Five 6" to 8" cichlids, one rainbow shark and a giant danio is typically more suited to a 75 gallon minimum tank size, for both water quality and aggression issues. And 40 ppm nitrates for any length of time can cause health issues with your fish. You need to shoot for a 20 ppm max and if you have higher then increase the size and/or frequency of the changes.

WYite

 

[Rbishop]

84 degrees sounds high, to me.
How long has this tank been established?
How many new fish added when?
What kind of test kit?
What kind of filtration?

 

[jake72]

Also what is the hardness of the water - the africans really need hard water.... likewise 84 seems suspect to me - esp the danio and dolphin cichlid (which didn't make it) really wants cooler waters.

Going back to water hardness the rainbow shark is going to have a bit of a time adjusting if the water is hard and if it is not hard the mbuna are going to really struggle.