Pair of Aplocheilus dayi «Sinharaja» (Sri Lanka)

The Ceylon Killifish (Aplocheilus dayi) is a species of killifish endemic to Sri Lanka. Aplocheilus dayi is one of the easiest killifish to keep and breed. They will eat flake food and are content to occupy the surface of a community tank. You can start your colony having just one breeding pair. The adult fish grow up to 8 – 9 cm if kept in a spacious aquarium and fed well on varied foods preferably live ones. Both sexes have a black dot at the rear end of the base of the dorsal fin.

A group of 10 fishes can be successfully kept in a 100-liter aquarium having a large sponge filter. No other décor is really required, except for the requisite tight-fitting lid. The spawning medium is a 5 – 6 cm long mop of green yarn with a slightly coarse texture, clipped to the top of the tank for easy removal or to a floating cork. For the best result, it is recommended to feed the breeding fish with live Artemia, Glassworm and Daphnia, although they will take frozen and dry foods. They eat with a vigorous snatching motion that is typical for surface-dwelling killifish. The temperature should be 24°C – 26°C with approximately 50% water changes every two weeks or whenever the waste built up.

After a few days of getting acquainted the eggs will be laid daily so that you have to check the mop and remove the eggs to avoid their predation. While spawning the male drives the female into the mop with a sideways pushing motion, and then the pair shakes as the eggs are released and fertilized. The eggs are 1 to 1.7 mm in size and hard to the touch. Pick the eggs and put them in clear plastic cups, so that fungus or development of eyes would be easily visible. To discourage the growth of fungus use a very strong solution of methylene blue, about two drops per cup.

Collect the eggs in batches of 7 to 10 days, letting them all soak in the chemical bath for a few more days before pouring off the blue water. Then put the eggs and fresh water in a shallow plastic container. Depending on the temperature, the eggs would start to eye up after about 10 days and hatch in 14 days. The fry are large enough to scoop up with a tablespoon or catch with a medicine dropper. Force hatch any eggs that had eyes, but had still not hatched after a couple of weeks by putting them in a jar with a little water and breathing into it before shutting the lid tight for a few hours.

Raise the fry in a 5-liter plastic container with an airline (gently aerated small sponge filter) and some java moss to provide cover and microbes for snacking. A killifish fry box works well with a little peat/coir and dried oak leaves in the bottom to condition the water and give the fry hiding places, and a ramshorn or other snail to clean up uneaten food and to provide food for infusoria.

The fry can be fed microworms and freshly hatched baby brine shrimp (BBS). In a few weeks transfer the fry to a 30-liter growing tank with a good sponge filtration, java moss and java fern, and a dimmed light above. The fry grow quickly on twice daily feedings of fresh BBS. The males began to develop their distinctive bright yellow-gold colour around 30 – 40 mm.

Use sand at the bottom with little addition of coir or peat and oak leaf litter. In about 5 – 6 months they can be transferred to a large breeding tank.

Species Summary:

  • Scientific Name: Aplocheilus dayi
  • Describer: Steindachner, 1892
  • Family: Aplocheilidae
  • Origin/Locality: Sinharaja (Sabaragamuwa Province, Sri Lanka)
  • Common Name: Ceylon Killifish
  • Disposition: Active top-dweller, recommended a species tank
  • Total Length: 80 – 90 mm
  • Spawning Method: Egg Scatterer
  • Breeding Proportion: 1M : 1F / 1M : 2 F / Large Group
  • Breeding Difficulty: Fairly Easy
  • Female’s Daily Clatch: 5 – 15 Eggs (depends on the female’s size and water conditions)
  • Incubation Period: 10 to 14 Days at 25°C – 27°C
  • Fry Growth Rate: Fairly Fast
  • Sexual Maturity: 5 – 6 Months
  • Life Span: 3 – 4 Years
  • Water Quality: Ordinary Filtration, 1/3 Water Changes Every Two Weeks
  • General Hardness:  5- 15 dGH
  • pH: 6.0 – 7.0
  • Temperature Range: 24°C – 26°C
  • Lighting: Dimmed Light and Dense Planting
  • Diet: Live and Frozen Foods (will normally accept dried foods too)
  • Keeping Difficulty: Fairly Easy

Pair of Aplocheilus dayi «Sinharaja» (Sri Lanka)

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