My late father owned a koi pond in his garden that has both Koi and Goldfish in. Unlike my father, my mother and I know very little about fish or fish care but are endeavouring to keep our inherited fish healthy.
A short while ago, one of my father's koi carp died, there appeared to be nothing physically wrong with it although it was one of our largest koi. (I'm not sure if this is related to the following but it may be relevant).
I have always noticed that the goldfish in the pond in particular seem quite 'fat' with large extended bellies, we assumed that they were pregnant and I have never given this much thought.
Today I found one of the fish dead, at the bottom of the pond, it had an insanely large stomach and on observation it seems that a few others may be heading that way also. I have attached some pictures below.
Does anyone has an idea what may be causing this? As I have said, me and my mother are no fish experts and we are desperately trying to avoid killing off my father's fish-stock.
The following points *might* be relevant in diagnosing: - The pond is about 6 or 7 ft deep and besides some water lilies there is not much shelter. (I have attached a photo of the pond below so you can get an idea). It is maybe 15ftx6 (maybe more). - We feed the entire pond large fish pellets that I think are primarily meant for koi, all the fish eat them though. - We have about 10 koi, 2 of which are quite large, and maybe 15 goldfish (although this is an estimate and I can recount). - My mother who feeds them often seems to put quite alot of pellets in and I often find them floating around on top of the water a long time after she feeds the fish. - We have a bead filter that we regularly clean out and backwash.
Looks like massive gasous bloating of the gut, possibly temperature,(temps have certainly been on a radical rise around the country this week) disease or diet related, so we will need to start getting into it some.
If this is hapening to multiple fish I assume egg production issues are out of the question even though the season isnt out of order, but its unlikely a number of fish would show egg related issues all at once, far more likely is an environmental cause, so any water quality readings you can get would be very useful, especialy temperature, if its constipation related its best addressed via diet, and Id doubt its parasitic as the fish are of otherwise good weight.
Id lay good money on it being down to the recent temp hike and possibly a bacterial reaction and oxygen saturation issue related to that hike. Get us the water readings and we can show you the best way to go about getting into it, in te meantime id get the pond a bit of shelter, even if it involves screening it off a little with corrugated sheeting, and try dropping in a whacking great airstone just to get the worst off the temp shock. Fish would have to be checked on a response basis after that, and possibly antibacterial pond treatments considered. Also stick with winter wheatgerm feeding for now, it will help with blockages, might even be worth giving a break from feeding altogether until the fish begin to metabolically righting themselves.
This is a big response even to the recent temp hike so please make sure you get those water readings, a decent API test kit and a decent thermometer should give you some good readings to go off if you havent got a kit. The pond is above ground and I assume it faces the sun for a good proportion of the day, so it will be very helpful to know its depth, and if it has a fundamental design flaw in its thermodynamics that could be making fish survivability within it difficult. It might be rectified easily with a pond cover, but we would still need to know the stats. It might hav a cooling issue in its design, might well find that day/ night temp drops and khikes are initiating the issues with the fish and bacterial infections taking the problem the rest of the way. Temp reading taken at midday and before dawn would be very useful. A full mention of stocking will help too.
Gotta say though, even if it has a thermic issue , I love the looks of the pond, very sexy .Bet that garden get bloody hot when the suns out though.
Thanks for the comprehensive post longhair, you certainly seem to know your stuff.
I'll acquire a pond testing kit and post up the results to see if anything has gone wrong. I'll also try and give the fish some more shelter and also try changing the food/feeding less to see if that helps. I'll also take some temperature readings and get a better estimate of the number of fish/get some full measurements of the pond.
About the airstone, I have no problem purchasing one, is there any possibility that it could damage the fish if oxygen is not the issue?
I'll post back soon, thank you so much for the help!