Aftyer cleaning my gals fish tank alll the fish started dying.

You should not use tap water only but pour the water where the fist live before in there as well. I wonder didn't people at the shop told you not to throw all the water but pour it in your fish tank? they should, the water helps the fish adapt better

There are many things that need to be checked.. the PH of the water can not be too varied from what the fish are in currently.. and also the Temperature they have to be slowly adjusted to the temp from the bucket they came from to the temperature of the water in the tank. That is why they tell you to leave the bags you bring them home in sitting in the water for 1/2 hour before you let the fish out into your tank. A shock in temp or ph could potentially kill your fish.

First don't take the fish out of the tank when cleaning it. Stress kills many fish. Never change all the water in the tank, as that is really hard on the fish meaning more stress. I suggest a small water change and don't clean the pebbles, as the tank sounds like it was over cleaned.

Hello deodavid, Sad story : you don't want to see something like this happening. 10 liter is a small aquarium, but I think you should do like for a large one, and not change all the water at the same time : it is very stressing for a fish, it kills bacteria useful for purification -- and without them ammonia and nitrites, toxic for fishes, will increase during weeks --, and it is difficult to know exactly the amount of chlorine in tap water, as it varies -- I think that chlorine killed your fish : 0.1 mg/liter is lethal for a fish --. Changing 30 or 40% of the water once every week or every 2 weeks -- and cleaning it roughly at this moment -- is probably enough for a 10 L aquarium.

If I understood well, you took out the fish of the aquarium, and let them back after cleaning? Seems like they had too many new things to adapt to at once. If you have a thermometer or water heater, you should check that the temperature is the same in the aquarium and the new water. There might have been too many chemicals in the water for the fish as well. It's not necessary to take the fish out all the time you want to change the water. When I had an aquarium I used to let 1/2 or 1/3 part of the water out using a small plastic tube. Then let the new water flow in the aquarium through that tube slowly. That way the fish will be less upset, and the temperature of the water won't be different. I'm sorry about your girlfriends' fish. I think they should have told you about the details where you got them. Some fish are very sensitive and even when you handle them carefully they don't like it, while others are not so much.

I think the fish got stress. They may couldnt adapt with the cleaning.. hehe

I've had fish for a couple years and have lost my share through trial and error. I'm no expert but I'll throw this out there anyway. One thing that jumped out at me, and I think some other mylotters touched on this in their own words, is the water change. Unless you are planning on putting a different type of fish in the tank you don't really have to take all the water completely out to clean it. If you do, you want to make sure you keep a substantial amount of the old water to put back in, say around 25%. This is to help the biological "filter," the friendly bacteria that helps get rid of ammonia and other harmful substances, to quickly reestablish itself. The bacteria lives mostly in the substrate(the gravel). When you clean the substrate that thoroughly you destroy the biological filter. Remember, the biological filter, once established, is the fish's best defense against harmful ammonia buildup. You can keep this in mind for the future. Just some helpful info. However, based on how quickly you said the fish started dying I don't think it has to do with a biological filter imbalance. Are you sure you used the right amount of water conditioning solution? And I assume you know for sure that your water has chlorine since you used conditioner to get rid of it. One thing about chlorine. In case you didn't know. Chlorine, based on what I've read by experts, can kill suddenly, and not always with symptoms. It's probably more lethal to a fish than ammonia. So, if you didn't use enough conditioner that might be a cause. Also, if you used too much conditioner it might be a cause as well. I don't know what conditioner you use but I use Amquel Plus and it does mention on the bottle that the conditioner will cause a moderate drop in oxygen levels in the water for the first few hours if aeration is not adequate. One more thing that another mylotter mentioned. Koi are a type of goldfish that just keep growing. They don't just grow to the size of your tank like some fish do. They will eventually outgrow your tank if they haven't already. I don't know how many gallons 10 liters translates into but I don't think a 10 liter tank is sufficient enough for koi. Koi are actually more suitable for outdoor ponds because they grow so big. I don't know if any of this info helps you solve your problem. If anything, hopefully, it will help make your water changes a little easier and more effective in the future.

Hello friend, It is very sad news. Hope they are ok. Have a nice day.