41 fish dead

[koi]

Well nothing is left except for a few snails i had in there. But what was weird was that the all died between plants. Would it be some kind of disease? Because it affected my shiners also they were swimming around fine until the shiners were added. But what i noticed about the shiner and rosy red that were left is that they were both Trying to squeeze themselves into the plants or swam against the sand on one side

[BeefyG]

Dead fish end up in weird places. They stiffen up and become little torpedoes in the tank current and can wedge themselves in all kinds of places. I would bet this is what happened unless you saw them swimming into the plants or sand.

[koi]

I saw them swimming into it well the shiner and rosy that were left they were doing that. Im still not sure when to add fish again.

[BeefyG]

When they are stressed out, fish often try to hide. If its an oxygen issue they will be at the top gasping. If its ammonia (I think) they will be at the bottom gasping. I think it was way too many fish all at once. I lost my first school of ruby tetras by adding too many fish at once.

When to add fish? Water change, water change, water change, test your water, repeat as necessary. Either do a full 100% water change or about three or more 50% water changes. If you don't have a test kit, do the water changes and then throw a cheap fish in there. Its not the most humane test, but its probably the cheapest. Build up your tank slowly. Even if its a schooling fish, they will be fine for a few days while you wait to add the other half or even third and then third of the school. The biological process in your filter needs time to catch up to each increase in bioload.

If you are adding feeder fish, keep them in a separate tank for at least a week and a month would be better. A 10 gallon bare bottom tank with a sponge filter will give you the simplest set up and the bare bottom will give you a good look at the fish and its poop. The small tank size will give you a good gauge of how many to add at a time. I had some shiners that were feeder fish that I brought home for a native tank. I had them a couple days when their skin started peeling off. Luckily I had them in QT.