I'm a little late but:
In the Wild
Calloplesiops altivelis, also known as a marine betta or Comet, can be found throughout recreational scuba depths, 10 - 150 feet (Debelius et al, 1994). They remain tucked tightly into crevices and hanging underneath caves during daylight hours. Rarely will they venture into direct light. Comets will become active only during night hours. "Active" is a relative term, however, as some may never venture outside of their cave by more than a meter. As nightfall approaches, they begin feeding. Their prey consists mostly of small crustaceans and small fish. They are slow feeders, often giving their prey a long stare prior to the attack. The attack is predictable; the Comet will hover slightly above it's prey with it's head lower than it's tail. All of its fins are fully opened, its pectoral fins are fluttering, and the tail is curled. Using it's pectoral fins, it makes a quick stab at the prey. Rarely does it miss. It will carry this trait into the home aquarium, though I've witnessed this natural instinct fade as the years progressed. I surmise it was the unnatural food that caused the natural "killer" instinct to diminish. The University of Texas at Austin has an excellent video clip of this feeding posture. To view the clip click here. It takes one or two minutes to download on my cable modem, so give it a few minutes after you click their link.
The Comet has two natural defenses. The first obvious defense is the false eyespot that is displayed near the rear of the fish. The real eye is virtually impossible to see. There are many other marine fish that employ this same defense. A common place for aggressive fish to attack is the eye. By having a false eyespot on the rear of the fish the aggression is averted away from the fish's real eye. The second defense, known as Batesian mimicry, is instinctive behavior that can occasionally be viewed in our tanks. The Comet will dive head first into cover at the first sight of danger. Rather than bury itself and completely hide, the fish will leave his back end viewable. To the potential attacker this looks similar to a Gymnothorax meleagris, the white-mouth moray eel, and usually results in the attacker withdrawing (Lieske, 1999). This defensive posterior can be viewed in the last three seconds of the above linked video clip.
In Your Aquarium
Prior to purchase ensure you have the proper environment for your Comet. The tank should have numerous crevices which are devoid of light. A cave or an overhang is highly recommended. Brightly lit tanks are not the best option, but as long as dark corners exist your Comet will be fine.
Getting a Comet acclimated to your tank conditions will be the biggest hurdle you'll have to overcome. They acclimate slowly to the aquarium. Once added, they will generally dive deep into your rockwork for up to a week or more. If you want to see your Comet more often during daylight hours, setup a cave or overhang that is devoid of direct light. Choose one corner or the other, not the center of the tank. This should avoid a good percentage of traffic from swimming fish. Avoid any direct light. Light reflected from the sandbed should also be avoided. However, make sure this cave is readily viewable, as you will initially need to sneak up to the tank to observe your Comet. Actinic lights are another great addition for additional viewing of the Comet. With a dawn/dusk photoperiod you'll get to witness the Comet in open water on a timed schedule. They tend to appreciate the softer light that actinics provide, and reward you with extended viewing of your fish.
Getting your new Comet to accept prepared foods is another tricky part of successfully maintaining this fish. I suggest trying prepared foods first, not live foods. It's probably best that your Comet not become accustomed to live foods unless it becomes necessary to induce a feeding response. Since Comets are night predators, night feeding might be necessary. Feeding during your tank's actinic phase is perfect. Try frozen/thawed mysis or plankton as your first offering. Most fish find this food irresistible. Small frozen/thawed krill or silversides would be another choice, followed by brine shrimp. It may take your Comet a week or more before it takes it's first food. I wouldn't concern myself until two weeks have passed with no feeding observed. Comets have a rather slow metabolism. After two weeks without a confirmed meal, I'd switch to live foods to entice feeding. Live freshwater mollies, ghost or grass shrimp, black worms, or brine shrimp should be fed. I suppose live peppermint shrimp could work as well. Eventually, you'd like to get the Comet weaned towards prepared foods. Long-term diets should include Mysis, plankton, Formula 1™, krill, and silversides.
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thanks!
