Family: Osphronemidae
A semi-aggressive carnivore osphronemidae from China — beginner-friendly.
Macropodus hongkongensis is a Osphronemidae. In the aquarium it stays semi-aggressive. Plan on 4.2–6 cm of adult fish at 18–26 °C. Related profiles: Macropodus opercularis, Macropodus erythropterus, Macropodus ocellatus.
Very — it's among the most beginner-friendly native Chinese gouramis. Wide temperature tolerance (18–26 °C), survives low oxygen (labyrinth organ), unfussy about water. Only two real duties: a tight lid against jumping, and one male per tank — two males will fight.
It's the most cold-tolerant Chinese macropodus, safe indoors above 10 °C and only at risk below 8 °C. South of the Yangtze basically needs no heater — a big reason it's lower-maintenance than Siamese fighting fish.
Fork-tail describes the deeply forked, swallow-like tail of mature males; black comes from the midnight-blue base body with red-blue iridescent striations — a fully colored individual looks like obsidian against a dark background.
Carnivorous leaning insectivorous: bloodworms, mosquito larvae, earthworms and small insects in the wild. In captivity, betta pellets plus frozen bloodworms work well; occasional live food noticeably improves color and condition. Small appetites — feed once daily, gone within a minute.
Classic bubble-nesting: the male builds a surface nest, the ripe female is added, and they embrace in spawning — he squeezes eggs from her and mouths them up into the nest. Remove the female right after; the male tends the eggs alone for 36–48 hours until hatching. Free-swimming fry take fine baby brine shrimp.
Males have longer finnage, a deeply forked tail and vivid coloration (red striations flare in breeding dress); females are shorter-finned, round-bellied and gray-brown. A visibly swollen belly with a protruding genital papilla means she's ready to pair.
Three common causes: too much light — dark backgrounds with subdued light color best, and fish raised against bright white often stay gray; no rivalry — letting two males see each other through glass fires up breeding dress; monotonous diet — add live foods and astaxanthin-rich feeds.
Small tanks (under 30 L) can run filterless with weekly third water changes — the traditional Chinese approach, and gentle flow suits their still-water origins. For larger or community tanks, a sponge filter avoids blasting their nests and swimming posture.
Apart from male-vs-male, they're broadly peaceful: small bitterlings, medaka, barbs and shrimp are safe (fry and shrimplets get eaten). They're far less aggressive than Siamese bettas and a versatile member of the Chinese native biotope tank.
The type population around Hong Kong has shrunk severely from urbanization and channelization of streams, and the species is assessed as Vulnerable. Captive-bred fish circulate widely in the hobby — buying captive-bred is both the practical and conservation-minded choice.