For the longest time we could not get our pleco (algae eater) to live. We had seriously boughten 14 of them in the last year. We finally got one that's survived. Then our goldfish got finrot and we lost all of them the last two we lost to old age. Only lost one to finrot. We did what the petstore said to do to clean and strealize the tank to be sure the bacteria are gone. We now have guppies. We started with 6 females and 4 males. We have now lost 1 of each with no signs of fin rot or anything. We've found one on the bottom of the tank and one stuck to the filter. We treat the water and everything and clean it often so we don't know why we are losing them. We had them for over a month before they started dying. And the males we got from a friend who has wicked talent when it comes to fish . The females we got from the pet store.
Does anyone know what is going on with them

Also we have very good well water that is tested each year not town water

Even though you have well water, it might benefit the fish to use a water conditioner (if you don't already).
Try using the product Cycle by Nutrafin for the first month after adding new fish. This will help stabilize the aquarium cycle and reduce the chance of losing fish.
As a rule of thumb, too much cleaning of an aquarium and it's filter does more harm than good as it removes the beneficial bacteria that removes toxins from the water.
Aquarium cycle
Good luck to you!

Well the tank isn't cleaned quite often. But I mean as often as it should. I think she cleans it once every few weeks. (it is my boyfriends parents tank but they don't know much about fish) one thing I think is the problem and I've been told it is but they won't believe us is that she shouldn't have two filters running in such a small tank. Its not big. More like 20 or 30 gallons or so

It's not bad to have more than one filter running at a time; however,
If the two filters are creating very strong currents in the small tank, the fish could be wearing themselves out which could lead to stress and be causing their deaths.
Look to see if the water is moving to fast in the tank, see if it looks like the fish are struggling to swim or getting pushed around by the currents.
If they are, see if the filters have a water flow adjustment on them, if they do, turn the water to a slow flow, if not suggest that she remove one of the filters... tell her that it looks like the fish are having a hard time swimming due to the currents.
Good Luck.

Thanks for the helpful information aketrue. We do use water conditioner. I see I forgot to answer that lol sorry. I read your post and went to metion it to her and I had noticed she had removed one of her filters already. Seems that we had some baby fish over the weekend and she was scared they would be sucked up by the bigger filter (which honestly was for a tank MUCH bigger then the one we have)

Baby fish update... there are to be exact. TEN little baby fishes. All of which are alive and well and beginning to show color and gender. We have also not lost a single fish since the second filter was removed and they swim much easier

That's great news. Good luck!