is it safe for my fish...

[staceyv]

to put a dead natural sea sponge in the tank?
i got it at the healthfood store (it's for applying makeup, but there isn't anything added to it). it's about 3 inches long/wide. is there anything in a dead sea sponge that could hurt the fish? (i have convict cichlids, red devils, firemouths and plecos)
please respond as i have already put it in the tank, and now i'm starting to worry that i should've researched it first!

 

[QTOFFER]

Welcome to AA, staceyv! Your first question here is a good one.

When I visited Tampa, FL a few years ago, I took a tour of a natural sea sponge processing plant. Immediately after hervesting, live sponges are immersed in an acid to remove the animals' proteinacious remains leaving only the sponge's skeleton behind. Sometimes the sponge is chemically bleached to lighten its color. After thorough rinsing, it is left in the sun to dry.

The following quote is taken from an article on sponges http://www.aquarium.net/0697/0697_1.shtml
"Depending on the sponge, the skeleton can be made of either mineral or proteinaceous material or both. The mineral material in sponges is either calcium carbonate or silica. Calcium carbonate is found in relative few, generally small, sponges. Silica, silicon dioxide, is the mineral component of most sponges."

Most sponges are silica based. This will not mess up your water chemistry, but it may fuel the growth of brown diatoms.
Sponges that contain calcium carbonate may increase your pH - something your SA cichlids would not appreciate. Do you have a pH test kit? Your fish prefer water pH 7.0 or lower.

I would also be concerned about any chemicals that may be in the sponge. During processing, sponges are rinsed thoroughly, so there should not be any traces of acid or bleach. You say that you got yours in a healthfood store, so it is probably free of perfumes or dyes. Still, I would have soaked the sponge extensively in water before putting it in the tank. I have read that you should never boil sponges because it causes them to shrink and become tough.

 

[ab92]

I put one in years ago and it disovled it looked like the inside of fish sticks floating around in my tank it was quite the mess.

 

[staceyv]

thanks guys!! i think i'll take it out of the tank!