Tannins and Fish

[julielynn47]

I know that a normal amount of tannin's will not harm fish, and that some fish really like them..My question is, is there a point when tannin's get to much?

I have started my 75 gallon, and I have driftwood in it....enough said I guess. I have quite a bit of driftwood, but I suspect the most of the tannin's are leaching from the hugh junk of mopani driftwood.

Anyone interested in the amount of tannin's can look at the thread about the 75 gallon. I posted pics there.

I want to add plants before I add the fish. I have been waiting to cycle the tank until the tannin's get lower. But this may take awhile and I am finding that I am kinda impatient with this. When it get cycled I really want to go ahead and add fish. But, once I start the fishless cycle I can't change the water...correct? So I can't do water changes to reduce the tannin's.

Sighhhhh what to do what to do what to do.... so my thoughts are, if I start the cycle and the tank is still this brown when the cycle is done, fish should be fine, even I can't see them in the brown water right? I guess I just don't know what to do. I have been so patient in setting up this tank, and my patience is about at its end. LOL

 

[Byron]

I have not come across specific "numbers" (for lack of a better word, as I'm not sure how one would "measure" tannin), but it likely depends upon the fish species. Tannins are simply organics and I have never found where these are injurious to fish. Fish species occurring in blackwater habitats live in water so dark it is described as resembling very strong tea. The pH can be in the 3's and 4's, and I would suggest your pH is probably a better thing to be checking.

I have found the light-coloured wood (like what you have in the 75g photos) to release more tannins initially than say Malaysian Driftwood. Water changes will slowly clear tannins, though within reason I would not worry about these.

Byron.