Will Tannins Harm My Fish?

Is will Tannins Harm My Fish really worth exploring? Read the pros and cons in our dedicated article.

Tannins are just organic material in the water, brackish water is dilute salt water. But if you want a blackwater pond (which is what I think you mean), I would just go with neon tetras or something similar. The pond will need to a decent size if it's only 4" deep, it will also need a filter.