Dabbling in Dicrossus: A discussion on sexing, spawning, and rearing under-appreciated dwarves

Dicrossus filamentosus male. Photo by Rebecca Goldring.

I first encountered Checkerboard Cichlids as a college student working at a local fish store. After years out of the hobby, my reentry vehicle was a small 19 liters (5 gal) tank. With my tiny tank I found myself wondering again about these small cichlids.

Eventually, I found myself with a 110 liters tank (29 gallon) tank and a pair of Dicrossus maculatus that were spawning regularly, but failing to raise fry. Searching for information on these hard-to-acquire fish didn’t turn up much, but I was able to find a source that suggested they liked soft, aged water, and were best kept one male to multiple females (Carey, 2010). So, I began to experiment. Two years, four rain barrels, two species, and seventeen tanks later, I’m finally getting somewhere.

While there are now five recognized species of Dicrossus, only D. filamentosus and D. maculatus are found by aquarists with any regularity. I will focus on only those two strikingly beautiful species.

The Boys From The Girls

Dicrossus are not as common in the fish trade as their more popular and flamboyant cousins, the Apistogrammas. Even if you’re fortunate enough to have a local fish store that isn’t a “big box,” you probably won’t find them regularly. Maybe, if you’re lucky, you’ll stumble upon a tank full of D. filamentosus. If and when you do find them, odds are they’ll be juveniles and odds are you’ll want a pair.

Dicrossus maculatus

Venture into my fish-room, and you’ll find two 75 liters long (20 longs) tanks dedicated to my Dicrossus maculatus. The tanks are furnished with decaying oak leaves, drift wood, and a few Anubias plants. The water is a mix of rain water and tap water, and gets a partial change once every few weeks. One tank has 2 males and two females; the other, one male and one female. The sex ratios aren’t ideal, but sexing these fish when they’re young is tough, and it’s not uncommon to have a “female” turn out to be male, though I’ve noticed a few reliable differences.

First, as mentioned in Randy Carey’s (2010) article, “The confirming feature lies in the caudal: This fin expands and starts to show vertical rows of spots which are absent in the female.” The tail shape and patterning that gives the Spade-tailed Checkerboard Cichlid its common name is a clear indicator of a male fish. As Carey also mentions, this trait does not develop until the fish nears adulthood.

Dicrossus maculatus male. Photo by Rebecca Goldring.

A second, less obvious difference is the shape of the ventral fins. Males tend to have longer, more pointed ventral fins, while the fins of females are rounder and more compact. The ventral fins on a male will eventually become long and trailing. Before the fins gain length, a thin, iridescent, blue line is usually visible on the anterior portion of each fin. The female will never develop this. If your D. maculatus has some sparkle in its ventral fins, it’s a boy! Females do develop color in their ventral fins, but not blue. Females that are not spawning often have orange ventral fins. The color may range from the dull orange-brown to a fairly bright red/orange. When the female is in spawning condition, her ventral fins change color, turning to lemon-yellow with a bold black stripe on the anterior edge of each. If you see a female displaying “crossing guard” fins, odds are she’s either guarding eggs, or will be soon.

The third visible difference is head shape. This one is a little harder to describe, but I always tell people that females are “cuter” than males. I’ve provided some truly terrible examples below.

Head shape. Photos by Rebecca Goldring.

Head shots of a male (left) and female (right) Dicrossus maculatus. On the male, note the slightly elongated snout and the location/relative size of the eye. There is also slight rounding of the head above and in front of the eye. On the female, note the short snout and location/relative size of the eye. The female’s eye is the same size as the males, but her body and head are smaller, giving her, proportionately, larger eyes. Big eyes=cute.

All three of these characteristics are evident in juvenile fish and may be helpful in ensuring you’ve chosen a female, rather than an immature male. As adults, these fish show clear sexual dimorphism, with the most obvious traits being size and the longer and more colorful caudal, dorsal, and ventral fins on males. Males reach a length of 10-11.5 cm (4-4.5 inches), and females grow to about 4.5-5.7 cm (1.75-2.25 inches). Females are also a little rounder than males when they are full of eggs, while males tend to maintain a streamlined shape.

Dicrossus filamentosus

Many of the traits that distinguish male and female in Dicrossus maculatus also hold true for D. filamentosus, the Lyre-tail Checkerboard Cichlids. There are noticeable, though less pronounced differences in head shape. Males also have more elongated ventral fins and similar iridescent blue striping. The distinct tail shape of the male makes these fish easier to sex. Even at a young age the male will show short points at the top and bottom of the caudal fin. These points grow into full streamers as the male matures, whereas females have a plain, rounded caudal fin. I’ve again provided some very rudimentary examples: Dicrossus filamentosus are markedly smaller than their spade-tailed cousins. Without their streamers, which can add up to 2.5 cm (1 inch) in length, males reach 5-6.4 cm (2-2.5 inches) and females reach about 3.8 cm (1.5 inches). Females also have a rounder body shape than males. When females are in breeding condition or guarding eggs their clear ventral fins turn bright orange. Personally, I am uncertain as to whether the change is permanent because my current females either always have eggs or are guarding fry. These ladies don’t mess around, or maybe they do.

Dicrossus filamentosus, from left to right: juvenile male, adult male, female. Photo by Rebecca Goldring.

Spawning Behavior

Spawning behavior is similar for both species. Males show off, fanning fins and puffing up, females wave their tails and curve their bodies a bit. In D. maculatus, males take on a dark on top, light on the bottom body coloration when spawning and really flare their dorsal fin, which is surprisingly tall. They dance and fan the females, who will sometimes respond aggressively. It’s not uncommon for fish to look a little beat-up after spawning. D. filamentosus are less aggressive in spawning than D. maculatus. Both male and female trade their checks for a pinstripe down the lateral line and the females’ ventral fins take on a tell-tale orange hue.

In both species, the female chooses and prepares the spawning site without the help of the male. The spawning sites vary and the fish don’t seem to be terribly picky. Anubias leaves and dead oak leaves are favorites for my D. maculatus. D. filamentosus seem to prefer dwarf lilies and swords, though I imagine that the preference of a specific plant is largely opportunistic. I’ve also seen spawns on sponge filters and uplift tubes.

The most interesting thing about the spawning site is not what they prefer, but how the chosen site impacts guarding and rearing behavior. For a site that is stable or attached to something (like a plant), the female patrols a wide radius and guards that site heavily. When a dead or detached leaf is chosen, these fish become mobile platform spawners; the female will carry around her leaf of eggs until they hatch.

Hatching and Raising Fry

Dicrossus filamentosus female. Photo by Rebecca Goldring.

The eggs of both species hatch after 2 or 3 days. Both species take newly hatched wigglers and pile them on a leaf, sometimes attached to a plant and sometimes on the bottom of the tank. For the first few days, females can be seen tending small piles of “glitter” and carefully retrieving, cleaning, and replacing any fry that fall. The stable platforms seem to offer a little more success. I’m not sure why, but if I had to guess I’d say it’s because it’s harder for the fish lose them. Females perform all parental duties without the help of their mates. I often have trouble finding my males after a spawn because they are so terrified of their female counterparts.

If you’re lucky, you’ll see the pile of wigglers after they hatch. If you don’t see wigglers, give it 7-10 days and try not to disturb the tank during this time. Females are good at hiding them, so wait it out and see if you wake up to free-swimming fry one morning. Once two weeks have passed, if you haven’t seen any free-swimmers, mom probably had a good breakfast shortly after they hatched.

Once the fry are free-swimming, the fun really starts! Remember those colorful ventral fins? Turns out they serve a purpose beyond attracting a mate. Females use those ventrals to direct fry and tell them things like “all-clear, come on out” or “go to sleep.” If you get this far, take some time to watch this cool behavior. It’s particularly striking in D. maculatus because of the yellow/black color combination on their ventral fins.

I feed free-swimming fry Golden Pearls, de-capsulated brine shrimp eggs, and micro-worms. They seem to do just fine on these foods, in addition to whatever they’re picking off decaying plant matter.

I’ve had better success pulling fry at 1-2 weeks free-swimming than letting the parents raise them. I think it may have a lot to do with my sex ratios. In both species, one male will spawn with multiple females within a few days. Randy Carey (2010) mentions the “problem” of skewed sex ratios in captive bred Dicrossus maculatus, with captive spawns producing substantially more females than males. I actually don’t think this is a problem, I think it’s by design. If you have just one female with a male, it’s pretty rare for her to successfully raise fry because the male will eventually buck-up, come out of hiding, and start looking for nookie. Eventually, the females cave, forget their fry (or eat them) and lay some new eggs. Carey notes that even wild caught groups of fish seem skewed female and he seems to suspect this is an issue of temperature. While I understand the desire to get “even” sex ratios (hey, then you can sell pairs!), I don’t encourage the attempt. Maybe playing with temperature can get you an even split, maybe it’s pH, but the bottom line is these fish don’t pair-off. Also, pairing them actually seems to inhibit their ability to raise fry because males will badger females into a new spawn before they have a chance to raise fry from the last spawn.

Both species of Dicrossus have a better chance of hatching eggs in soft, acidic, aged water. For D. maculatus, I’ve had success with a pH of less than 4 and water temperatures in the mid-high 70s. D. filamentosus seem to be a little more tolerant, and eggs will hatch in a tank with a pH of less than 7.0 (low-to mid 6s) and temperatures in around 24 C (70 F). Given that there can be mild aggression during spawning, I’d recommend keeping a trio in no less than a 75 liters long (20 long) aquarium. Make sure there’s plenty of cover in the form of leaf litter, driftwood, and live plants, and include small dither fish to bring out protective maternal behavior in your females. I often chose small pencil fish, like Nannostomus marginatus, because they stay towards the top of the tank and have small mouths. In my mind, this makes egg predation less likely.

Dicrossus maculatus pair. Photo by Rebecca Goldring.

Final Thoughts

If you keep these fish, you’ll have problems. You’ll have problems finding them, you’ll have problems getting the sex you asked for, and you’ll have problems getting them to successfully raise fry. If you keep these fish, you’ll also have a lot of fun. They are beautiful, intriguing, and have lots of personality. They make a great centerpiece for a small show tank, or a fascinating breeding project. These guys probably are not a project for a “one and done” breeder, but if you like to get to know your aquarium residents, you’re in for a treat. Remember to take time and have patience. Most importantly, watch your fish – really watch them. Lose hours in front of them. Take some serious time with them and someday you’ll be teaching me something about them.