Tropical fish?

Question

Ive owned tropical fish for a number of years now, having had no problems. last weekend i emptied the tank and moved the fish to a temporary tank and gave the existing tank a blimin good clean.
I filled the tank up, and allowed the tank to warm to the correct temperature. My usual procedure is then to test the water to check for copper ect, which came back fine.
My poor fish apart from 3 have died. whats gone wrong?
In the years i have done this its never happnened!!!
My only theory to why its happened is i introdued some new fish to the tank a few days earlier. Would they have maybe had a disease and spread it on to my healthy fish?

Thanks in advance.

Answer 1

You probably cleaned your tank too well. It sounds odd, but the fish need to have some of the bacteria in the tank to survive. The fish produce ammonia as part of their wastes, and this is toxic to them in fairly low concentrations. Bacteria use the ammonia as a food source, and convert it to nitrite (which is also toxic to fish) and other bacteria convert the nitrite to nitrate, which your fish can handle in moderate amounts.

When you cleaned the tank, you removed all the bacteria, so now those wastes are building up (plus you added more fish and more wastes). Eventually, your bacteria will build up again, but in the meantime, you may need to do a few more partial water changes to remove the ammonia and nitrite that the bacteria you do have can't process. If you have a test kit, use that to monitor the concentrations of ammonia and nitrite so you know when a water change is needed. Don't add any more fish until the ammonia and nitrite aren't detectable for at least a week. In the meantime, don't be surprised if you notice your tank water getting cloudy - this is a side effect of the bacteria loss/cycling. It should go away within 2-6 weeks.

You also get this happening when you set up a new tank, or when you use medication that destroys your tank bacteria.

I'll put some info with more details for you below.

Answer 2

Completely cleaning out an established tank is usually not a good idea. There are always going to be beneficial bacteria in an established tank that help control the ammonia levels created by the fish waste. When you do a thorough cleaning like that, you wash all the bacteria away and you have to start all over again. I'm pretty sure that after doing that and reintroducing all the fish(with the stress of some new ones) into an uncycled tank, the most likely cause of you deaths were due to ammonia poisoning. The ones that survived were lucky and hardy and most likely some of the ones you've had the longest. In the future, I would only do partial water changes. You can use a gravel cleaning attachment on your siphon and there are gravel cleaning products you can have without siphoning off the water. Good luck in the future!

Answer 3

That could be or maybe you removed too much good bacteria with the cleaning and then with the added fish the filter and good bacteria couldn't keep up with the added waste. Did you check the ammonia levels after the cleaning?I've always been told not to clean everything at once, so i just do the inside of the aquarium (walls and such) one week then then next week I might clean off the heater and intake on the filter, then the next week if its time I change the carbon filter. But I do 20% water changes once a week also. But I'm still new to the hobby, just started my tank 2 months ago.

Answer 4

I'm so sorry to hear about your fish. It sounds like you may have 'reset' the tank's cycle. Even if there were no nitrates or nitrites in the water right after you refilled your tank, without the natural cycle continuing in the same water, nitrates and ammonia cannot be gotten rid of. Next time, don't take all the water out of your tank.
This water is the natural buffer and is adjusted to the bacteria that live in your filters and in your gravel. If you want to give your tank a good clean, consider investing in a gravel vac, an algae scraper, and decoration cleanser.

Answer 5

It could be that the fish were stressed.
If the tank had been established for a while, the water you emptied out could have had higher levels of things like ammonia, nitrates, and nitrites. When you cleaned it this dropped these levels back if not to 0. In doing this, when the fish were put back in, the water conditions were way different then they were originally. Your fish could have acclimated to the old water and went into shock in the cleaner water.
Sorry for your loss. Good Luck!

Answer 6

Did you use a chemical to clean the tank or just water?
You should never empty a fish tank after it has cycled unless you have no fish to go back into it again. The tank was not cycled and wasnt ready for fish.
Sorry for your loss.

Answer 7

It might have been the new fish.

Another explanation could be that the tank's had a mini-cycle because you've emptied all the water, so ammonia's built up and poisened the fish.

Did you dechlorinate the new water before adding it?

Hope you get to the bottom of it.

Answer 8

You destroyed the bacteria that break down waste by cleaning it out.
Putting a bunch of fish in at once overwhelmed them with their own waste.

http://fins.actwin.com/mirror/begin-cycling.html

Answer 9

i agree with the above. you probably cleaned it too much