Q. I’ve been reading your magazine for about a year and have been keeping freshwater aquariums for about seven years with no difficulty. I decided that I would start a saltwater aquarium recently. It’s a 44-gallon aquarium that’s not near a window. I have one 10,000K and one 18-inch actinic tube. I put five damselfish in the aquarium after about four weeks (I put them in one at a time over the course of a week, not all at once).
I have had no problems at all. The pH is 8.2. Nitrite, ammonia and nitrate are 0, and salinity is 1.022. About a week ago, I bought live rock from a local pet store and put it in my aquarium. The next day, I lost two damselfish. I tested the water, and everything was fine except nitrites, which were 0.25 ppm. I did a water change after losing another damselfish, and the water tested perfect. I just lost one more saltwater fish, and I am upset. I think that the live rock I put in triggered this. Do you think this is possible? What should I do? Thanks for all your help.
A. It seems that you did things a little out of sequence. We start marine aquariums with damselfish or other hardy saltwater fish to allow the aquariums to build up beneficial bacteria. The live rock is the best place for these bacteria to grow, and the usual sequence is to run the aquarium a few days to allow the salinity to stabilize, then put in all the live rock. After, add the starter fish all at once or over a few days, and monitor the ammonia, nitrite and nitrate. If the live rock does its job, ammonia will spike first and begin going down, with nitrite then following the same pattern. Finally, with ammonia and nitrite at virtually 0, nitrates will settle to a reasonable level.
One thing that would explain your problem is the condition of the live rock. Was it fully cured? Did it give off any odor, and was it sloughing off various things? If you bought live rock that was not completely cured, the curing process could easily kill even the damselfish.
I hope you have a good protein skimmer on the aquarium. Run it at the highest output you can, and keep dumping all the nasty, smelly stuff from the collecting cup. Let the live rock run for a few weeks, then start over again with damselfish to establish the nitrogen cycle.
Most importantly, find a good local fish store where the employees are knowledgeable and are interested in helping people with their fish, and follow their advice.