Random fish dying

[Kingunis]

Hi I am new to this site. But U have had a tank for about 7 months.

I had a 10 gallon tank with 2 albino Cory catfish, 1 rainbow shark, 1, silver tipped shark, and 2 tiger barbs. They all lived happily with no issues at all for 7 months till a few days ago I decided to go to a 20 gallon tank so they could have more room. So I cycled the new tank and what not then I slowly transferred over all the fish the other day. They all seemed happy till I wake up the next morning to find all the fish dead except for the 2 albino corys.

So I decide to go to the LFS later that day and i pick up some various new fish and 2 more albino corys. I get the fish home and put them in the tank within about 4 hours one of the fish died. So I figured it had too much stress, untill I wake up the next morning to all the fish I bought dead except for 4 albino corys (2 from the original tank and 2 new ones) a new silver tipped shark I bought and a new rainbow shark.

Later that day I notice the silver tipped shark dying, it basically go vertical and motionless then start to sink then all of sudden it would come back to life and then go motion less again and sink over and over each time the motionless stage getting longer untill it finally died. The rainbow shark is still alive and looks healthy and all the albino corys are doing perfect.

Anyone know what is causing this. Is it a bad batch from the LFS? Why is that only the albino corys seems to doing so well?

Also I had my water tested and it came back good levels. Nothing to high or too low.

 

[Mumma.of.two]

Hi!
What are the exact numbers if ammonia, nitrite and nitrate? What did the shop use to test? Strips can be highly inaccurate. Did you move any filter media from the old tank to the new tank? It sounds like your tank is cycling. Start off with a large water change with temperature matched dechlorinated water. Id advise buying your own liquid test kit like the API master test kit.
http://www.aquariumadvice.com/artic...-to-Starting-a-Freshwater-Aquarium/Page1.html
Please read this.
Just some info on your fish.
Silver tipped sharks need schools of 6 or more of their own kind to feel comfortable. they also get really large needing a 125g tank.
Rainbow sharks need a 55g tank minimum. They are solitary so only one per tank can be kept.

 

[Kingunis]

I'm not sure of the exact numbers of the levels. The shop did use test strips which I have heard can be in accurate. So I will most likely go out and buy the master test kit. As for the filter media, no I did not use the same one from the old tank. It is the same Type of filter which is a penguin bio wheel 150 but it was brand new along with new media. I have done 2 water changes to the tank since this has started happening both about a 30% - 40% change

 

[Mumma.of.two]

Ok. Your tank is cycling. You've lost all the nitrifying bacteria in the move. What you need to do is large water changes (50-60%) daily until you can get you test kit.
Follow this guide until your tank cycles again.
http://www.aquariumadvice.com/artic...g-but-I-already-have-fish-What-now/Page2.html

 

[Kingunis]

Ok. Thank you for the link