Elassoma is a genera of seven Pygmy Sunfish species that occur in scattered populations from North Carolina down to Florida, and along the gulf coast to Eastern Texas and as far north as Illinois. In cultivation they are most often available as wild-caught specimens, although their care and breeding is straightforward if the founding stock is healthy and adults are fed a hearty diet.
Elassome gilberti, the gulf coast Pygmy sunfish are the only species I have experience with. I started with an adult pair from Aquarium Zen (Seattle, WA) in winter of 2020. Thanks, Aquarium Zen! They were worth the drive 🙂
Ideally one pair or a small harem is housed in a tank no smaller than 10 gallons. For each additional male 5+ gallons should be added. They thrive in soft water with a pH of 4-6, but are tolerant of a wide range of conditions. No heater or filter is necessary, and they likely do better without them. A light is useful for keeping plants alive but not otherwise necessary if ambient light can provide a day/night cycle. They seem most comfortable in shadows, so any light used should be on the dim side. The roots of floating plants or dense stem plants, guppy grass, even algae, provide perfect hiding places for these fish. They also will utilize leaf litter. Water changes should be fairly infrequent, they do not produce much waste, and a healthy cycled aquarium with only a few fish per ten gallons should just need to be topped off every so often. Below is the aquarium when first setup, looking very silty.
After two or so weeks,
The biggest potential challenge in keeping these fish is that they require live foods. Live blackworms or bloodworms are some of the best staples, although some individual fish will take frozen food. Ideally any keeper would secure a source of live worms or learn to culture their own before obtaining these fish. Even though adults only reach 1-1.5 inches, they can easily consume multiple full blackworms or bloodworms in a single feeding. Baby brine shrimp, Vinegar eel, banana worm, Walter worm, and Grindel worm make excellent food for younger fish and supplemental foods for adults. Baby brine eggs can easily be found online or at your local fish store. Hatchery equipment is varied depending on your needs. This one was recommended to me and for someone doing baby brine for the first time, worked perfectly. If feeding alot of baby brine, it helps to have two cultures going at once (on different cycles) so you always have some available.
Both male and female fish are very shy, usually darting into a mass of plants when someone approaches the aquarium, but, if you sit there for a minute or two they often resume whatever it was they were doing, all the while sort of looking at you from the side. Except when startled, they move more like gobies, very slowly, deliberately, with alot of control over the speed and direction, and what seems to be very observantly. They will often track a moving worm for a while before consuming it, and they are good hunters. They do not readily consume their own offspring, and are very peaceful ~ all in all, a very smart fish! Unfortunately they only live a few years, so if you want to keep a group going, it is often easiest to breed them continuously, as this genera of fish seem to be only sporadically available.
A note about other tank inhabitants- I’ve never introduced other species but due to their slow peaceful nature and what I have read online, would not recommend keeping with other species. Maybe other shy reclusive fish that take a long time to eat live food could be ok (at best), but, their behavior is interesting enough on their own to not really need additional fish, and I suspect courtship behavior would be very hindered by any schooling fish, larger fish, or perhaps even other small peaceful fish. Without the opportunity for breeding behavior, the keeper would be missing out on much of what makes this fish so special to begin with.
Males are somewhat territorial, but mostly chase eachother without inflicting any damage to fins, and multiple males can co-exist in a 10+ gallon tank. When displaying, the male flutters his fins, and moves his entire body up and down rapidly. His colors darken when courting, and fade to a paler blue-brown. A male fish might chase a female around relentlessly, but generally, he maintains a distance until the female shows interest. I haven’t seen egg laying take place, and have only once observed the clutch of eggs ~ an inconspicuous blot of sand-colored spheres towards the bottom of the aquarium, surrounded by algae and positioned near a corner. Fry hatch out shortly after, I think in a matter of days, to a size hardly perceivable with the naked eye. A 40x jeweler’s loupe is a useful tool for distinguishing fry from aquarium debris or bubbles. The eyes are enormous, and the only easily identifiable feature on otherwise transparent fry. They seem to account for about half of the fry’s total volume at first.
Below, a male displaying courtship colors. I had a hard time capturing the colors correctly- in person, they are a very dark blue, almost inky black, and very iridescent.
When they first hatch out, they are a similar size as baby brine and not large enough to eat them. I am not entirely sure what they eat at this time. I suspect their diet included microfauna present in the river sludge that was used as substrate (?), in addition to the vinegar eel, Walter worm, and banana worm that I fed about once a week. When they are large enough to eat baby brine, you will be able to see through, to the pale pink brine in their stomachs.
In another tank, with multiple pairs, I only fed live black worms for the entirety of the breeding cycle, and a few babies grew to adult size. It is possible they are cannibalistic when no properly sized food is available but I can’t say for sure.
It was difficult to observe them eating as they spent almost all their time in the top inch or two of the aquarium, directly in the dense roots of floating plants. No predation from the parents was observed, and subsequent offspring were not hunted by their siblings either, at least not that I saw. Juvenile fish will gladly consume brine, and even smaller live worms, and I suspect they eat snail eggs because a boom in offspring decimated the snail population and I saw no snail eggs for the better part of a year. Steve at Aquarium Zen also made this observation. Once the fish matured to adult size, I began to see snail eggs again.
Once they are large enough to consume full worms, they put on the rest of their size very quickly, a juvenile can double in size in two weeks at that time. For a few months, I was unable to source live worms, and instead fed smaller food, mostly brine shrimp. During this time, the adults maintained their weight, but the juveniles stalled in their growth. Immediately when worms feeding was resumed, they all began to gain weight quickly. They are resilient fish, and I suspect they could survive a long time on smaller foods, but I do not think it is sufficient for growing fish, or sustaining breeding activity in mature fish.
A subadult fish, below. Likely a female. Until fish are about half their adult size, it is difficult to discern their sex. Subadult males tend to not court females in an aquarium with alot of other subadults, but if they are separated out and paired off, they will usually start courting and displaying breeding coloration very quickly. Sibling fish seem to get along quite well overall, and the original 14″ cube my pair was in at one point had over 40 subadult fish in it and no aggression was observed, although there was sometimes quick movements in regards to securing the best worms at feeding time. That aquarium now has 15 or so adults and there is frequent courtship displays by multiple males and no fin-nipping or aggressive behavior, other than quick chases, that I have observed. The reason for the higher density is that I do not know what to do with the fish and can only dedicate two aquariums to them at this time. If you happen to live in Portland, OR or are stopping through and want to keep these fish, and can provide them with a good home, please get in touch.