Dead Goldfish

[pelmetman]

We have a small wildlife pond and have loads of frogs, toads and newts. However, due to the high number of mozzies around the pond I decided to buy a couple of goldfish as they are good at eating them.

Only had them a week and yesterday noticed one was dead in the shallow end with two revolting shrimp/prawn like things either side of it. As I said the poor fish was already dead but these things appeared to be squeezing the fish and when I got the fish out there were no marks on it at all except its mouth was wide open. They were about two inches long and grey in colour.

Dave wonders if they could have been young crayfish?

Anyone got any ideas please.

[MKG]

We almost had a tadpole extinction in the couple of really hot days recently - it's down to deoxygenation of the water (especially where it's shallow). If it gets really hot for an extended period, chuck in a bucketful of water from the tap or, better still, let water fall from a hose supported at a height. That'll stop fish from suffocating, which is probably what happened to yours. The shrimpy beasties are unlikely to be crayfish unless you live very near to a crayfish-packed river or lake. But there are quite a few species of freshwater shrimp around, a few of which can grow to that kind of size. They usually come in with plants or fish bought from elsewhere. What they won't have done is killed your fish - they're scavengers.

Mike

[pelmetman]

Hi Mike

Thanks for that, I feel really bad if it is because the poor thing suffocated, it has certainly been hot lately and yes the water was obviously warm.

I don't know for sure but I have heard there are crayfish in the dykes in Lincolnshire, I will have to keep my eyes peeled and also make sure the water doesn't get too warm. I wish now I had'nt introduced them and stuck to the original wildlife pond.

Sue

[Carltonian Man]

Sounds like the shrimp things could be great diving beetle larvae. They're quite voracious and, I believe, will attack goldfish (my fish used to beat a hasty retreat and hide whenever one rose to the surface).

[Carltonian Man]

I meant to say. If they are diving beetle larvae with the big pincers, you can maybe use a net to remove them from the pond but for more difficult areas around plants etc. goad it with a small diameter stick and just lift out when it latches on.

[pumpy]

Be aware that putting tap-water in ponds will increase the algae levels (especially in sunny conditions).

[MKG]

Absolutely correct, Pumpy - I should have added "as an emergency measure". If the pond is seriously deoxygenated, you need to get oxygen in AND cool it down as quickly as possible, and tap water is the best way I know of to do that. But yes - don't make a habit of it.

Mike

[pelmetman]

We have always topped the pond up with rainwater.

The bottle green water appeared before I got the fish so cannot be caused by their food etc. Also there is no weed just green water!

Thanks for all your help though. Sue