Q. I'm 15 and have kept fish for the last few years. I've been thinking about keeping a bigger aquarium (30 to 55 gallons is what I have in mind). I now have a pair of red zebra cichlids (Pseudotrophus zebra) in a 10 gallon; the male is about 1 ½ inches, and the female is an inch. I was told that eventually they would need a bigger tank. So, I plan to set up a mbuna cichlid tank. I am hoping to keep Pseudotrophus demasoni and some Labeotrophus fulleborni cichlids with my P. zebra. I've read that L. fuelleborni is a good algae-eater. Other than that, I haven't found much info on this fish or P. demasoni. Could you give me some details on these fish? Also, could you tell me if my plan for at least a pair of each would work for either 30 or 55 gallons?
-- Harold Bosstick

A. Whether you can keep pairs of African cichlids together in a tank is a hit-or-miss thing - and mostly "hit," in that they will really scrap with each other, especially when they begin to breed. Your existing 10-gallon tank will be too small for the pair of zebras, and the male may beat up the female. If they do breed, and you notice the female holding eggs, remove the male as soon as possible.

A 30 gallon should be all right for two pairs, but you would be better off going with a 55. To keep three pairs would require a 100-gallon tank or larger. In either case, provide plenty of rock piles in different parts of the tank, so each species should be able to establish and hold a territory.

The other way that some people keep mbunas is to crowd so many of them into a tank that none can establish a territory. This is a dangerous, and I do not recommend it. The tank must be heavily filtered if you have that many fish in it, and you cannot miss doing weekly water changes.

If you have a big enough tank with enough rockwork, you may find some surviving babies that just show up sometimes. If you want to get a good amount of babies, however, you should remove any female that is holding eggs (it will be very obvious: the buccal cavity, the fancy name for her throat, will be visibly distended). You can either put the egg-holding female into a tank of her own (your 10 gallon would be fine), or you could strip the eggs from her and hatch them in a hatching tumbler.

Labeotrophus fuelleborni require vegetable matter in their diet, but they are not a fish we would normally refer to as an "algae-eater." They will, in fact, munch on algae in the tank if it is to their liking, but they do not necessarily clear algae from surfaces the way that Plecostomus, Ancistrus or Otocinclus do.

Include plenty of vegetable matter in the diet of all African cichlids. You can do this by feeding any of the foods prepared specifically for Africans. You can also provide them with Spirulina flakes or disks three times a week, which are pure Spirulina algae and which they will love. If you want to give them regular vegetables, the best are spinach, romaine lettuce or squash. Put them in the microwave for a minute or two to break down the fibers before feeding them to your fish.

Live Rock Not Cured
Q. I've been reading your magazine for about a year and have been keeping freshwater tanks for about seven years with no difficulty. I decided that I would start a saltwater tank recently. It's a 44-gallon tank that's not near a window. I have one 10,000K and one 18-inch actinic tube. I put five damsels in the tank 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 tank. The next day, I lost two damsels. I tested the water, and everything was fine except nitrites, which were 0.25 ppm. I did a water change after losing another damsel, and the water tested perfect. I just lost one more 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.
-- Bobby Seeringard

A. It seems that you did things a little out of sequence. We start marine tanks with damsels or other hardy fish to allow the tank 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 tank 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 damsels.

I hope you have a good protein skimmer on the tank. 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 damsels 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.

Water Change Volume
Q. I have a 55-gallon tank with an 8-inch red devil. I do water changes twice a week and have two Penguin filters (a 170 and a 125). For water changes, I use tap water (pH 8.0), Biosafe and Seachem Discus Buffer to keep the pH at 7.0. After a water change, it turns slightly cloudy but clears up about the time another change is due. I have thought about changing to a liquid pH reducer to lower precipitating calcium and magnesium. Or maybe I'm cleaning the gravel too much and need to use a bacteria starter with the water changes. What should I do?
-- Charlie Wainwright
Biloxi, Miss.

A. Congratulations on doing a good job of the most important aquarium maintenance chore: water changes. You say that you do water changes twice a week, but you don't say how much of a change you do each time. You may simply be doing water changes that are too large. I suggest no more than 10 percent of the tank volume if you stick to the twice-a-week schedule, especially given that you have only one large fish in a 55-gallon tank.

It's possible that with just one large fish, doing large water changes may not be giving the beneficial (nitrifying) bacteria a chance to get established in the water and on the surfaces of the tank before you change another large volume of water. It also is possible that there is too much waste from uneaten food. Finally, you do not say how much gravel you have and how you vacuum it. If you vacuum the gravel too much, again you may not be giving the good bacteria a chance to get growing. I hope this helps.