Putting coal in your aquarium?

Question

I have 2 rocks/pieces of coal in my aquarium is this bad? is it bad for my fish? reply ASAP PLEASE!!!

Answer 1

I know that filters have coal for filtration, but I haven't heard of having it in your tank. I can't see it being bad because if you have it in your filtration system and it helps and doesn't kill your fish I think it would be ok. I would suggest to talk to a pet professional just to be sure.

Answer 2

It wouldn't be my first choice for a decoration, but how it will affect your tank will depend on the type of coal and amount/size of the pieces in it.

"Coal" is a pretty general term. There's anthracite and bituminous coal, and they have differences in the hardness and some differences in chemical composition. That's not saying a lot either, because there are differences between different layers of coal found in the same area. The biggest concerns I would have in using it are the potential for a high sulfur content (sulfur, when mixed with water creates sulfuric acid) and the potential for heavy metals to be present (iron, magnesium, manganese, copper, and others) which can be harmful to fish and plants if found in high enough concentrations (and what's present will vary with where you live/source of the coal). When wet, these substances can dissolve if the water becomes acidic (and here's where the sulfur comes in) and become even more toxic to aquatic life. That's why streams affected by acid mine drainage have so little life in them. And I'm not talking just about streams with the orange precipitate of iron hydroxide ("yellow boy") - these are the streams where recovery is taking places and the harmful substances are precipitating out - it's the ones that still seem pristine with crystal-clear water but no aquatic life whatsoever that can be the most affected. Bituminous coal will probably present more of a problem than antracite.

A few small pieces in a large tank probably wouldn't be too harmful, but why take a chance? You can arrange the coal in a display around the tank if you like. Or seal the pieces with an aquarium-safe sealant to reduce the possiblity of leaching chemicals into your water.

Answer 3

I have coal in my aquarium. Just a couple of decorative pieces. They've been in there since May with no problems. Just make sure you scrub them very well before putting them in.