dying fish???

[sharkhunter]

Hi, on behalf of a friend, he has informed me that all or most of his carp are dying in his moat. The moat is fed by a small spring that always runs and and drains off into the river/stream. He tells me that the moat seems to be stagnant due to lack of flow on the outlet but the spring still runs? He also mentioned that he has coypu living in the moat and has seen them on his lawn regularly, could these be the cause of his fish dying?? Could their tunneling be the cause of the water being diverted underground and not into the moat?? Do Coypu carry/have Weils disease and would they kill of fish. Any help would be appreciated, Hugh.

[Deimos]

I am no expert (and others do feel free to correct anything I say) but;

Ragondin are herbivores and would not kill/eat fish. However, they do tunnel extensively into river and lake banks, though I have no idea if this could cause the spring to be diverted (probably depends on the detailed geography.

Rangodin can carry Leptospirosis (sic) which I believe is the same as or similar to Weil’s disease. However, I have not heard of it affecting fish.

Probably not much help

Ian

[Ron Avery]

Carp are of the goldfish family and get the same infections etc, it could be a lot of things killing them, but from what you describe it is more than likely the lack of oxygen in the stagnant water.  He needs to get some air into the water quickly by a pump or even splashing his feet at the edges would help.

Has he examined the corpses for signs of illness, growths, inflated stomachs.  Does he feed them? Has he stopped feeding them yet?  As the water cools down their systems slow down and food can literally rot in the stomach and poison them.  Ian is right,  Weils disease will not kill fish, it is common where there are rats urinating in "still" water, but it will not killl fish.

[sharkhunter]

[quote]Carp are of the goldfish family and get the same infections etc, it could be a lot of things killing them, but from what you describe it is more than likely the lack of oxygen in the stagnant water. ...[/quote]

Hi thanks for your reply. I will pass on your thoughts to him. As to the feeding, yes he does feed them but since his summer visitors/ family have left i believe that he has stopped feeding, i will try to get a look at some of the corpses and check for growths etc.

I do know that he has taken some water samples to take to a local lab in Riberac, perhaps Sogedo may do a test for him?? Will inform you/forum when he gets results if any, many thanks, hugh.

[Motorhead]

Check for redness around the operculum (gill cover). This is a sign of ammonia poisoning which can mimic the effect of low oxygen levels. 

Ammonia may or may not show up in the lab test as the nitrosomas bacteria may have converted it to nitrite by then.