Cycled sponges from other tanks

[Diamond Discus]

I was thinking, I used cycled sponges from my existing discus' tanks for my 2 new groups of Malaysian imported fish and they are doing great. In essence wouldn't using these sponges be just like adding an existing fish to the new ones? In other words are they developing immunities to the existing fish already just by having their sponges in with them?

[KJoFan]

Sue, I don't have the answer for you, but I have always thought the same exact thing. You are supposed to QT very strictly but yet add a cycled sponge from an existing tank, that has all the "bugs" your current fish have in/on it. Or at least, that's how I see it.

But perhaps you are right in that they are developing immunity. Honestly, when I start up a new tank with fish I rarely used a cycled sponge in the new tank. If I'm doing big heavy water changes, like I do, I don't feel that ammonia and such is going to be a huge problem.

However, the experts would probably disagree. ;) I'd be interested to hear others' opinions on this.

[William Palumbo]

Hi Sue,

In theory I believe you are correct. Not sure if the new fish are developeing immunities to your existing fish, but as of right now they are just not being affected by it, and maybe never will. I think the real problem to worry about is "if" you place the sponge filter BACK into the old tank, with your existing fishes.. I always start my new fish off like you, with seasoned filters with no problems. I ALWAYS treat any new fish as a potential plague to my existing stock, usually never the other way around...Bill

[Diamond Discus]

Thanks Karen.... and Bill, that was my next question. You are saying not to use these sponges again for existing fish. So I guess that rules out using them when I want to move my pair back to the 55 gallon tank after these guys go to the big tank.

[Graham]

Sue Transfer a Guinea pig fish over to the QT for a week or so before combining all the fish. This way you're sure that everyone is safe with each other....the sponge will be safe also is the fish are ok

[Diamond Discus]

Sue Transfer a Guinea pig fish over to the QT for a week or so before combining all the fish. This way you're sure that everyone is safe with each other....the sponge will be safe also is the fish are ok
Thanks Graham. I will do just that!