You don't mention much of a description but I'll make a wild guess and say you put in a Pleco or Plecostomus. It is black or dark grey and the size varies a lot because in it's normal environment it grows quite large. It is very popular and widely available but it is a tropical fish and won't survive a cold winter in the pond. Sandy

Thanks Sandy. Yes, it's called a Plecostomus. I googled it and there was a picture. Darn I should have done my research on them, but I completely forgot I put them into my pond. I'm going to have to go out there and get them out. There are only 2. Will the dead fish affect my pond at all? It's ice cold and the dead fish are a solid ice cube.

Thanks!

IMO two dead fish in a 4' deep pond won't hurt the water quality, even when they eventually decompose, but I'd net them out when/if you can. Sorry about your loss, ponding is always a learning experience.

i doubt the fish would harm your water quality much, but I recommend removing it ASAP. We had some nasty mold stuff growing in our pond and on a few fish. Luckily it went away and the fish are still alive two years later. You might get a rotting stench once the water warms up also, its a horrid smell.
Brian

To answer your question, the fish that live through winter in places with snow are those fish from places that have snow in winter. Koi and Goldfish can survive the winter are long as they don't freeze solid and their water is not fouled by ammonia, H2S or other contaminants and they do not run low on Oxygen. Other fish that can survive winter are for example, rosy red (A.K.A. fat head minnows), most sunfish (or bream for Southerners) like pumpinseeds and bluegills, most of the North American minnows like shiners, smallmouth & largemouth bass, bullhead cats, ...

I have a small pond in N.E. Ohio and I have 12 fish in it. All different varieties of large goldfish or chubunkins. The fish will be fine if the water is at least 3 foot deep at it's deepest end, so it wont freeze solid. The amonia that is put off by their waste is what will kill them more often than the cold, if there isn't a hole in the ice for it to escape. I have a small floating heater in mine and it keeps a spot open. If you can't do that, then place a milk jug with a bit of water in it so that it floats. It will keep the ice from freezing solid where it is. I miss feeding my fish in the winter, hurry up Spring!!
I hope this helped you,
Kathy
ps, and yes, like was mentioned above, all good advice, is get the dead fish out if you can, but dont crack the ice if it is frozen solid on the top, you can hurt the fish.

I have just been kinda learning as I go with my pond, sort of impulsive. I've kept indoor aquariums for years, kept many types of fish manly cichlids..

My pond is only about 17"-19" in the center area and I guess about 150 gallons. I'm making it bigger each year (hard to find what to do with that horrible heavy clay dirt thou!). 2 6" Koi and 8 other 3.5-4" fish (i get carried away, too many fish). The pond does get sun, probably too much during the summer until the floating plants spread.

I was planning to bring the fish inside but did not set up properly so I left them out too late to bring in. I did one partial water change in December. The water temp did go up to 58 degrees F last week during a warm spell but has gone down to 40 earlier. Fed once this winter when it warmed up last week (they were very active so I couldn't resist) I have a power head moving water at the surface 24/7. I bought a Pondmaster de-icer before the last cold snap a few weeks ago but it never came on.

So will they survive okay? Should I take out a few of the goldfish (to reduce the ammonia load) I am less fond of to keep them all from dying?

Noki, your pond is really too shallow to guarantee survival in your zone. It needs to be about 3 feet deep. With enough aeration you might get away with less but it is a gamble in normal winter temps. Your pond is really too small for so many fish. I know, I know, it is such a temptation. They are so pretty.
Clay is a problem but I dug enough for 1000 gallons and I'm an old lady with health problems. I was seldom able to use a shovel. My main tools were a garden fork to break up the soil, a small chain saw to cut the roots and various small trowels and utility blades. It was a real job all by myself and it took most of the summer but I got it done. With enough air and filtration you may luck out but before the normal weather returns you need to reduce that fish load or enlarge the pond.
I don't know how that power head is helping but most of us on this forum use air pumps or the kind of bubbler you use in an aquarium. The big problem here is the exchange of the gas that builds up in the water so a bubbler at the surface isn't helping to stir things up much.
That gas is toxic and must be able to escape which is why there needs to be a hole in the ice. That de-icer won't click on until the water temps are right around 32 to 36oF. It has a thermostat built in to control that and will only keep a small hole open around it. With no ice it should not turn itself on.
Don't feed the fish. It is a real temptation when they are begging but if the water turns really cold it could kill them. Fish don't have stomachs to process the food and it just stays in their gut and rots. The cold temps shut down their metabolic processes. This is a difficult winter since the temps are not holding as steady as they should but the fishies can feed themselves on bits of algae and other stuff we don't notice. If you must feed, try frozen peas with the skins removed. Cook the peas. They are a mild laxative.
Best of luck to you for the rest of this winter. Post any more concerns you might have on your own thread. Sandy

I found bird skeletons in my pond last spring and the fish were fine but if you can get them out , then do it ASAP . Rick

I have a pond measuring 20'×20' ×20"-24 "deep. I found out heaters are a huge waste of money! All you need is a nice aireator with 3or4 lines with air rocks. I've had my pond and some fish for 15 years and that keeps my pond wide opened in the winter. I'm in indiana and we get 10-20 below at times. I have never lost a fish in winter. You can buy the aeriator and black jungle tubing on Amazon for under 60.00! Well worth it,just make sure your aeriator is shielded from the rain and snow!!

It is always a good idea to remove dead fish asap. As they decay, they release nutrients and oxygen is used while they are breaking down. A good cold water bacteria will help any pond be healthier over the winter months.