This tiny little fish caught my eye quite some time ago, and I finally procured a breeding pair (and an extra male, somehow) at the beginning of June 1997. I kept them in a little 5 gallon tank with black sand and many empty shells until February 1998, when I moved the colony to a 10 gallon tank and added some rocks. The fish use the shells for hiding and spawning, and are known as shell-dwellers for this reason. Males of this species rarely exceed 2", and the females are considerably smaller, usually just over 1". Their behavior is very interesting to watch, and given the right conditions, they are easy to breed.
I keep the water at a temperature of 80 degrees, and the ph is naturally about 8.2. The water is very hard. I use an air-driven sponge filter only, which is safer for the very tiny fry. When the fish were in the 5 gallon, I used an incandescent light/hood, and though they bred well in the tank, it was just too easy to neglect, and turned into an eyesore. Smaller tanks need much more frequent maintenance, so I've moved them into a 10 gallon with a fluorescent light and glass canopy in hopes that evaporation (and algae) won't be so bad.
I feed the fish a variety of foods, though they do just fine on plain tropical fish flakes. I rotate tropical fish flakes, spirulina flakes, and dried bloodworms, and occasionally they will get a few days of nothing but live baby brine shrimp, which they LOVE. I started out doing water changes every other day when they were in the 5 gallon tank, but found they did just fine with a daily topping off and then a 25% water change every other week... then I got lazier and lazier and I think they went nearly a month with no new water, and the water level went down about three inches (which is a LOT in a 5).
So I decided to clean the 5. I removed all shells and fish (which are easy to net if you take the shells out first and if they are larger than an ant) and put them into a 5 gallon tote tub. There was one little guy... not much more than a speck... maybe the size of a flea... that was left in the tank, and I never was able to get him. The fish remained in this 'tub' for nearly a week before I moved them into the 10 gallon, into which I had put the sand from the 5 (washed and washed), as well as some nice 'holey' rock from my yard. Since I've moved them, I've seen hide nor uh... scale... of the tiny babies that I was able to catch. My assumption is that the larger fish will occasionally eat their young... or maybe they just died. I estimated that I put about 30 fish into the 10.
I discovered something when I moved the fish. They stay with their shell, not with their mate. I accidentally put the papa's shell on the right side of the new tank, and the mom's shell on the left, next to the shell belonging to the bachelor. The original papa fish has rounded up some of the larger young females, and the original mom and her new mate have spawned several times since then.
I've noticed these fish will breed anywhere there is a small space... not just in a shell. One day I turned the light on and lo and behold, there were three little fry ducking in and around the base of a rock, in the mouth of a tunnel dug by the parents.
Multies dig. It's what they do. They are little bulldozers with fins. Don't even bother arranging the sand with a slope from back to front... huh uh... won't matter, because in a few days you will have a tank full of hills and valleys (all the way to the glass!). Thick layers of sand can cause problems with anaerobic bacteria, so I was careful to provide only a thin layer this time. They still made a mountain out of it, covering the nice large pebbles I'd put in the center of the tank, as well as a few of the smallest shells that the fish had moved there (rejects, I suppose).
The fish formed two distinct 'properties' in the tank... each male on his own side of the mountain, each with several shells. Occasionally the two males will meet in the middle and display to one another. Most of the smaller fish stay in the back of the tank among the rocks, leaving the shell pits to the adults (which chase them out), and eventually, I assume, the smallest fry. I am wondering if this is something that is occuring because they were just moved, or if it's the 'way it is' all the time. In the 5 gallon, there wasn't a lot of room to establish territories like that, and everyone pretty much stayed together. I also kept a static population in there, even though new fry appeared from time to time and grew... it was the larger fry that were disappearing.
Because of this, I would remove about a dozen of the larger fry at a time to another tank to grow to a salable size. I would feed them the same as the breeding group, but I did not add sand or shells to the tank. Instead I provided cover with small flowerpots that had holes cut into the sides. This made it very easy to net them when the time came, and the tank stayed scrupulously clean since I was able to vacuum ALL debris from the floor. The fish are ready to go at about 7-8 months of age... nearly all of them are right at or just over 1" by that time. I'm sure they'd grow faster if I fed more live foods, though :-)
When I discover new babies, I feed something they can eat... either live baby brine, Wardley's Liquid Fry Food for Egglayers (messy but good), or the Tetra powdered fry food for egglayers, which I soak first so it will sink. When they are large enough to handle crushed flake, I stop the baby food. Of course it NEVER hurts to feed live baby brine... or frozen for that matter (I dislike the odor of frozen brine, but the fish don't seem to care one way or the other). I should probably feed it more often than I do. I hear that these fish appreciate live and frozen bloodworms as well.
Feeding behavior is fun to watch. When I put foods in that float on the surface, the whole group of fish will rise slowly in a great mass, and 'grab' a mouthfull of food and dive... dive fast... to the safety of the shells. They do this in unison. It's very interesting. When I feed live baby brine, or something that sinks, they stay in the bottom half of the tank and make funny little jerky motions as they pick the food out of the water column, only doing a mass 'dive' if something startles them. My guess is that these fish are not normally surface feeders... or must be very careful to avoid predation.
Eventually, I'd like to move the colony to my 20 gallon long and just cover the floor of the tank with empty shells. These fish have proved to be a favorite of mine... their interesting behavior and good looks merit them the best seat in the house.