Q. A friend and I have been breeding fish for some time and we wish to breed angelfish, but we can't find out how to tell the male from the female other than when they are spawning. The books in our library either say that there are no differences or state that there are minor differences, but without explanation. We can't afford to buy a group of angels to raise to adulthood, so identifying them by gender is our only option.

A. Compared to many cichlids, angelfish are indeed difficult to sex. However, there are two differences that will allow you to distinguish male from female. The first has to do with the shape of the head. Angelfish are highly derived cichlasomine cichlids, in which many males develop conspicuous bumps on their foreheads when sexually active. Angelfish do not develop such nuchal humps, but males do have a much more rounded cranial profile than females.

The second difference relates to the shape of the ventral profile. In male angelfish, the outline of the body between the insertion of the ventral fins and the origin of the anal fin slopes sharply downward, whereas in females this is a straight line.

Before you rush off to select your future breeding pair, however, I must make a couple of cautionary remarks about the breeding of angelfish. The first is that these distinctions apply reliably only to full-grown angelfish. The second is that there is a sound reason for securing a pair via the group rearing method that has nothing to do with assuring that you have individuals of both sexes.

When working with monogamous cichlids, it is unwise to assume that any two individuals of the opposite sex will pair successfully. Cichlids with such a mating system — and angelfish are among their number — can be extraordinarily choosy about their partners. Attempts to pair two incompatible individuals are far more likely to end in mayhem than in matrimony.

The easiest way to avoid this problem is to raise a half dozen youngsters to maturity together and allow them to select their own partners. I suspect that if you compare the cost of buying a half dozen quarter-size angelfish with the purchase price of two full-grown specimens, you will find the difference in cost is negligible.

As for the extra adults, retailers are always happy to acquire adult angelfish, so it's usually a simple matter to swap such specimens for credit toward the purchase of fish or supplies. Alternatively, there's always a local aquarium society annual auction. Well-grown angelfish never want for buyers in such a setting and often command very impressive prices.

Back to Kribs
Q: I have a 20-gallon tank with a pair of kribensis, Pelvicachromis pulcher. The books I've read say that to get them to spawn, separate them until the female fills up with eggs. How can you tell when she is full of eggs? Can I leave both of the parents with the fry once they are free-swimming?

Q: I have a male and three female Pelvicachromis pulcher, all about 2 inches long. Can you explain to me why only one female is carrying eggs? Also, how will I know when two of the fish have paired off?

A: Because your questions about Pv. Pulcher complement one another, I have decided to answer them together. To address the first question, segregating the sexes during the conditioning period is often recommended to aquarists wishing to breed egg-laying fishes. Its purpose is to both lower the prospective breeders' threshold of sexual arousal and preclude the possibility of unregulated spawning.

Such an approach works well enough with fish whose reproductive pattern does not feature a protracted post-spawning association of the sexes — egg-scatterers such as tetras, barbs and so on fall into this category. So do species in which only one parent cares for the eggs and young, such as male loricariid catfishes and labyrinth fishes, or female mouthbrooding cichlids.

Common kribs, like other representatives of the genus Pelvicachromis, are monogamous, substratum-spawning cichlids characterized by a preference for completely enclosed spawning sites and the long-term defense of the free-swimming fry by both parents. Monogamy in this context describes the exclusive association of a single male and female for the duration a single reproductive effort. Courtship in such cichlids is for the formation of a stable bond between the male and female prior to spawning. Keeping the two sexes separate in order to condition the female is hardly the best way to bring about this state of affairs, and is particularly inappropriate for Pelvicachromis species, in which pair formation is preceded by an extremely lengthy period of courtship.

Commitment to a monogamous relationship varies among males of cichlid species. In some species the association between the sexes appears to depend upon the sex ratio. If females outnumber males, the mating system may shift towards sequential polygyny, in which a male will prematurely abandon the care of his progeny to the female and pair with another female — a behavior observed in a number of New World cichlid species. In the extreme case, a female-biased sex ratio will cause the male to shift from monogamy to harem polygamy, in which he maintains a simultaneous relationship with two or more females — characteristic of a number of Lake Tanganyika Lamprologus species.

Although the marked sexual dimorphism of Pelvicachromis species in both size and color suggest otherwise, these cichlids are quite monogamous. Offering a male a selection of potential consorts may increase the likelihood that he will find a compatible mate. Once he has made his choice, however, a male krib will persist in his commitment despite the presence of other females. Both male and female of a pair will treat unpaired females as any other territorial intruder. In answer to the second question, such concerted aggression toward other fish, repeated over a period of several days, is an unequivocal indication that the individuals in question have paired. If the tank is large enough to allow these fish to move beyond the limits of the pair's territory, there may be some benefit to allowing them to remain as target fish. Otherwise, they should be moved to less stressful surroundings.

False spawnings, preceded by suggestive intensification of the female's coloration and the even more suggestive swelling of her abdomen, are to be expected, particularly from young pairs that have never spawned before. This tendency to play house usually drives novice breeders to distraction and may lead them to question the pair's compatibility. Such behavior is perfectly normal, and the aquarist willing to exercise patience will eventually be rewarded with a successful spawning. The appearance of the female's ovipositor, a blunt white tube located immediately posterior to the anus, is the clearest indication that a pair of kribs is in earnest about spawning. The female's refusal to leave the pair's previously selected spawning site, coupled with her refusal to permit the male's entry, is an equally unequivocal indication that they have done so.

As is the case in Apistogramma and their allies, hygienic behavior in Pelvicachromis is an exclusively female responsibility. I suspect that recommendations that the male krib be removed from the breeding tank immediately after spawning arise from belief that this behavioral convergence portends the same sort of exclusively maternal defense of the mobile fry that characterizes these Neotropical dwarf cichlids. In point of fact, a week after spawning, the female will bring her school of chunky-bodied, mottled fry out into the open, where she will be joined in its defense by their attentive father. In my experience, male Pelvicachromis are exemplary fathers whose presence contributes significantly to the survival of their fry, particularly if the pair has spawned in a community setting.

A final observation is that it is not unusual for a young pair of kribs to eat their first few spawns. This is certainly a disappointing turn of events, but it is not cause for serious worry about the pair's compatibility. Should this occur, I suggest you simply regard it as behavioral quirk the pair will eventually grow out of.

Simply exercise a bit of patience and you will be rewarded by the exemplary parental behavior that makes the common krib such a desirable aquarium fish. I wish both of you the best of luck in your krib breeding endeavors.