Can a tank previously used for reptiles or other animals then be used for fish?

I never realized this, and may have done it before and just not noticed, but I was recently told by a friend who used a 75g tank for snakes.

When he converted it into a fish tank, his fish kept dying. When taking water to LFS to check, they had told him the previous animal had left too much ammonia in the tank, and a good amount of it was absorbed into the silicone sealant.

Supposedly this was extremely toxic and he could not keep fish alive or his levels down for weeks. It took a lot of money and a great deal of work and time to finally get it down.

Has anyone heard of this or can anyone tell me their experience?


I just tore down a 90g which was inhabited by rare Albino Tree Frogs and now I wanted to make it a new fish tank.

Any suggestions on how to clean it out?

Thanks much

i have heard that you have to reseal it and clean really good

btreut wrote:

i have heard that you have to reseal it and clean really good

Yes! You will have to reseal it as silicone will dry out and cause leaks if filled with water. This is why when buying a tank that has been sitting empty for a long time, you should only fill it with water and wait a few days (I wait a week minimum fr my own satisfaction) in case of leaks. (When I worked at a pet store that sold both fish and reptiles, the manager for the reptiles had told me the silicone will dry out)

As for cleaning, I cannot help you there, I have never had to; but my thoughts would be it would be easier (and a bit safer) if you stripped and resealed the tank.

which is the sealant to use again?

You can use GE I or GE II.I've used both and never had a problem with either.You can go to your LFS and spend alot more for the aquarium silicone.

the clear aquarium sealant. I dont now any brand names, but your lfs should have it

BFinley wrote:

You can use GE I or GE II.I've used both and never had a problem with either.You can go to your LFS and spend alot more for the aquarium silicone.

hehe, or what he said ^

the lfs sells the small tube of aquarium sealant for alot, i'm asking about the equivelant which is sold at home depot in a larger tube for alot less..

I think something like GE G1 or something?

Yes you can use the GE 1 or the GE 2 from home depot.Alot cheaper.Thats what I use on all my tanks.I just resealed a 100g about 2 weeks ago with the GE 1 silicone and its up and running African cichlids in it.

Thank you

Ur welcome!Anytime!!

I. Agree

if you use Ge silicone II be sure there are no additives and never use silicone that is "mildew resistant". GE silicone I is a safer bet if you have never used silicone before to reseal a tank. (be sure to wear rubber gloves)

i have some that were reptile tanks and my method is if the silicone looks and feels good then ill fill with water and let it sit for atleast a week and if it dont leak then ill use it with no worries if it does leak then i might reseal it unless i find someone to buy it for a reptile tank

I usually soak all reptile tanks with bleach water for about a week....The big thing I always worry about is if soap or other detergents were used on tanks. They seem to leave a residue and are toxic in many cases.