Species description

Care, breeding and tankmates

Fish profile

Temperament

Peaceful

The Pygmy killifish is extremely peaceful, shy, and somewhat reclusive if not provided with enough cover. When kept in appropriate numbers in a well-planted tank, they become curious and active, exploring every leaf and crevice. They are delightful, gentle fish perfectly suited for a dedicated nano setup.

Diet

Carnivore

They are micro-predators that feed on tiny invertebrates and zooplankton in nature. In captivity, they require tiny live or frozen foods such as microworms, baby brine shrimp, and daphnia. They may eventually accept very finely crushed, high-quality flakes, but live foods are crucial for conditioning.

Sex ratio

Group

Males are more brightly colored and slightly slimmer, while females are plumper and usually have a distinct spot (ocellus) on their sides. They are best kept in a group with a ratio of one male to two or three females to disperse male courting attention. Keeping them in groups encourages their natural, fascinating social interactions.

Feeding frequency

Twice daily

Due to their tiny stomachs and active foraging behavior, they should be fed very small amounts multiple times a day. Two to three micro-feedings daily is ideal to keep them healthy and active. A well-established planted tank will also provide a natural source of infusoria for them to graze on.

Bioload

The Pygmy killifish has an exceptionally low bioload due to its diminutive size, rarely exceeding an inch in length. They produce very little waste, making them ideal candidates for small, heavily planted nano aquariums. Excellent water quality must still be maintained, as they are sensitive to pollutants.

Flow

Strong

They originate from stagnant swamps, bogs, and slow-moving backwaters heavily choked with vegetation. They prefer very gentle or almost zero water flow in the aquarium to mimic these calm environments. Sponge filters are highly recommended to prevent them from being exhausted by strong currents.

Jump risk

Yes

Like most killifish, they have a tendency to jump if they feel threatened or if water parameters decline. A secure, tight-fitting lid is essential for their aquarium. A thick layer of floating plants can also help deter them from jumping by making them feel safer.

Reproduction

Oviparous

Breeding is relatively straightforward in a dedicated, heavily planted setup. They are plant spawners that will lay their eggs among fine-leaved plants like Java moss over a period of several days. Providing abundant hiding spots is necessary so the fry can hide from the adults, who may occasionally eat them.

Compatibility & tankmates

Species only

They are incredibly peaceful but easily intimidated and outcompeted by larger or more active fish. They should only be kept in a species-only tank or with other tiny, peaceful tank mates like dwarf shrimp or microrasboras. Keeping them with aggressive or fast-swimming species will result in them hiding constantly and starving.

Tank level

All levels

They utilize all levels of the aquarium but spend most of their time weaving through dense vegetation in the middle and upper levels. They require a heavily planted tank with low lighting and plenty of cover to feel secure. They will rarely venture into open water without immediate access to hiding spots.