Fish died - any help or ideas?

[snailbuddy]

This tank is a 20g reef 4 months, pc lighting, 2 filters, 4 powerheads, 20+ pounds live rock, substrate, 2 small ocellaris clowns, 1 bi-colored blenny, a collection of small corals, 2 cleaner shrimp, 2 fire shrimp, 1 emerald crab, 4 tiny hermits, several snails. I only use RO water, do 10% changes once every 2-3 weeks. I fed the tanks and noticed a clown in obvious distress. I tested the levels, all perfect except for nitrates - 80 ppm. Did a 25% water change, nitrates down to 40, fish still in distress. Couldn't find the other two fish. By morning, the clown had died, still can't find the other fish. All inverts and corals are doing great. No sign of disease on the fish. What the heck? OK, I know I've been over feeding - bad, will stop - feed frozen brine, mysis, etc. Use marine snow, combo vital, plancto. Any ideas what caused the fish to die? Am doing another 25% water change today. Thanks for any help!

[Beverly]

What is your tank temp?

[snailbuddy]

Temp is between 78 and 80

[Beverly]

Nitrate at 80 ppm is high, but probably not the cause of death of your fish. Because all died at one time, and your corals and inverts seem to be okay, I can only think that the fish were all sick and you couldn't tell that they were. Or, perhaps something toxic got into the tank that only affected the fish. Gads, there's nothing worse than losing fish when you have no idea what caused it

I would like to offer a few maintenance suggestions:

1. Do weekly water changes of at least 15%. Yeah, it's a PITA at first, but once you get into the groove, your tank's inhabitants will really appreciate your efforts You will also experience fewer nuisance algae problems in the long run.

2. If you have any mechanical filtration, thoroughly clean the media in changewater every week. Doing so will preserve the bacteria, but remove the crud buildup that helps cause high nitrate and phosphate levels which cause nuisance algae.

3. Check alkalinity, calcium and magnesium levels at least every two weeks. Maintaining these three important chemistry components in your 20g will help your corals thrive instead of struggle along. Here are some links to help you understand reef chemistry and how to correct imbalances:

Aquarium System Volume Calculator:

http://home.comcast.net/~jdieck1/volcalc.html

The Reef Chemistry Calculator:

http://home.comcast.net/~jdieck1/chem_calc3.html

Reef Aquarium Water Parameters:

http://reefkeeping.com/issues/2004-05/rhf/index.htm

Magnesium in Reef Aquaria:

http://www.advancedaquarist.com/issues/oct2003/chem.htm

Solving Calcium and Alkalinity Problems:

http://www.advancedaquarist.com/issues/nov2002/chem.htm

Sorry to hear about your fish Hope the above suggestions are useful to you

[snailbuddy]

Thank you so much for your input! I will follow your advise to the letter. I feel so bad about the little fishes . . . they were so happy. I'll follow up on the links you gave me - looks like great advise. Thanks for the time you put into helping me - I really appreciate it. I should be able to avoid such problems in the future thanks to you!

[Beverly]

You're very welcome, snailbuddy