Female rainbow fish dying

[Beau Burkhalter]

I have had two female millennium rainbow fish  die in one day. Both acted very strange just before death. Dashing around, and gasping. I noticed that they look red and swollen around the anal area. Of course, nitrite 0, ammonia 0, nitrate around 20. Water is a tiny bit tannic but the Ph 7.5 and pretty hard water. Oxygen level is good also. No visual signs of distress or physical changes. They were in with two other females and two males. Making it four females and two males in all. They were kind of young and not much breeding yet. About two and a half inches. No other predators in the tank. Driftwood and Pogostemon Stellatus Octopus. 75 gallon. 77 degrees

Edited February 7, 2022 by Beau Burkhalter

[Colu]

How long have you had them before they died have you added anything new to the tank resently 

[Beau Burkhalter]

On 2/7/2022 at 10:55 AM, Colu said:

How long have you had them before they died have you added anything new to the tank resently 

No nothing added for several months and they have been in there for about a year

[Colu]

With the red anal area I would be suspicious of camallanus the fact they kill fish with in a month and you haven't added any thing in three would rule them out I would add an extra air stone have you done a water change resently and did you use a water  dechlorinator also were they eating ok before they died it's possible that something like a clearing product got in to the tank causing them to have a reaction

Edited February 8, 2022 by Colu

[Beau Burkhalter]

On 2/7/2022 at 3:23 PM, Colu said:

With the red anal area I would be suspicious of camallanus the fact they kill fish with in a month and you haven't added any thing in three would rule them I would add an extra air stone have you done a water change resently and did you use a water  dechlorinator also were they eating ok before they died it's possible that something like a clearing product got in to the tank causing them to have a reaction

No water changes recently. They are in a tank with lots of other community fish and other rainbows of the same species. All other fish are fine. Very strange

[Colu]

On 2/8/2022 at 1:52 AM, Beau Burkhalter said:

No water changes recently. They are in a tank with lots of other community fish and other rainbows of the same species. All other fish are fine. Very strange

Nothing else is coming to mind at the moment the fact that it only affected two with in a short space of time is odd

Edited February 8, 2022 by Colu