Water quality concern

[cheletnjared]

For the past week or so, I have not seen my manderin goby. It has been a part of my tank for about 8 months. I know that it likes to hide out in the rock structures, and feeds off of microverts on the rock and in the sand bed. Recently (about 4 weeks ago), I upgraded my 2" sand bed to a 5"-6" sand bed to improve my water quality and stability. I also added a firefish (like the one Omegatron used in the thumbnail to the fish database forum), about 2 weeks ago; and it seemed to be doing well with my foxface.

I think that it probably died from the addition of live sand (lack of proper food) or the firefish harassed it to death. What I am worried about is that the dead fish is polluting my water. I have looked at Ammonia, Nitrate, and PH levels, but everything seems to be doing ok. It is very difficult for me to look for the fish, as that would entail taking about 70 pounds of live rock out of the tank (that is if it is on the right side of the tank where I usually saw it). I guess that my real question is: is it possible that my sand bed and skimmer will be enough to stabilize the tank until the goby is completely decomposed? OR should I take everything out and find it?

My game plan so far is to continue to monitor the parameters, keep my skimmer on 24/7 and do weekly 10% water changes for the next month or so. If that is enough in your opinion, how long do you think it will take until I am in the clear?

My tank is a 55 gal. with a 30 gal. sump. It has 200 lbs live sand, and about 120-140 lbs live rock. 3 x 36" VHO. It also has a recently added Aqua-C Remora Pro skimmer, and has been up and running for a total of 2 1/2 years.

Any comments are welcome. - Jared.

[kevinpo]

Jared,
IME in a well established tank like yours a small fish will be decomposed in about 3 days. So if it has been missing for a week there will be nothing to find. Just continue to test for water quality parameters (a small water change couldn't hurt).

A 55 gal tank IMO is marginal for long term good health of a mandrin (not that it can't be done, just not easily). A 90 gal works fine as long as there are no other strong competitors (like hawk fish, wrasses, etc.).

Fire fish (Nemateleotris sp.) should ignore a mandrin. In nature they are planktivores feeding from the water column.

HTH,
Kevin

[cheletnjared]

GOOD NEWS!! The oddest thing happened yesterday while I was cleaning my tank. Usually when I clean my tank I neglect the inside of the overflow in back of the tank. This time, the algae that had been building up on the inside of the overflow column got to the point that it was clogging several of the holes at the top of the overflow. This caused the water that was still coming in to come in a lot faster at those points, which resulted in a very noisy overflow. (I will definately be installing a Durso Standpipe or some sort of mod. after this experience.) Anyway, I decided to remove a large particle prefilter in the column and clean out all of the algae in there. Once I started cleaning and removed the prefilter, I noticed that there was something moving in the bottom. I got out the ol' fish net, and found that it was my long lost Manderin Gobie! It had somehow managed to squeeze itself through a 1/2" space and go for a ride down the overflow waterfall. What is still amazing to me is that it managed to survive in about 4" X 2" X 3" of water for about 5 or 6 weeks! I guess that it just kept on eating the copepods and amphipods and whatever else came it's way.

I was going to remove it from the system because of the DSB, but now I figure that it has earned it's right to be part of the tank. Besides, maybe it heard me talking about taking it out and decided to hide out for a while until things cooled off.

- Jared.