Rostratus
Fossorochromis rostratus
Cichlidae
About
The rostratus, or Malawi sand diver, is one of the largest haplochromine cichlids of Lake Malawi, reaching around 25 to 28 cm as it cruises the open sandy floors off shallow beaches. It is a dedicated sand-sifter that takes mouthfuls of substrate and strains out buried invertebrates, so it needs a broad, uncluttered sand bed to behave naturally. Unusually calm and non-confrontational for its size, it is a fine centrepiece for a spacious hard-water tank, though it grows large and swims constantly, demanding real length and volume rather than height.
Care
Keep one male with several females in a long, open tank of 450 L or more (180 cm ideal) with a deep, soft sand bed for natural sifting, plenty of swimming room, and hard, alkaline water at pH 7.8-8.4. Peaceful for its size but active; avoid pairing with nippy or highly aggressive mbuna.
Diet
Sand-sifting omnivore that strains buried invertebrates from the substrate. Feed cichlid pellets plus frozen mysis, brine shrimp and bloodworm, and keep a soft sand bed so it can forage properly.
Tankmate compatibility
Avoid (271)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Extended finsStrong · from about 8 months, and later in a suppressed male
On many cichlids and killifish the male's dorsal and anal fins draw out into trailing points as he matures, while the female's stay rounded.
- VentingA hint only · only on a mature fish, easiest when she is in breeding condition
The method breeders use when the answer has to be right. Hold the fish upside down in a wet hand or soft net and look at the two openings ahead of the anal fin. The forward one is the anus; the one behind it is what you are reading.
- Adult sizeA hint only · only across animals of the same age
In many cichlids, catfish and loaches one sex simply grows larger — usually the male, though there are well-known reversals.
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Frequently asked questions
- What tank size does a Rostratus need?
- A Rostratus needs an aquarium of at least 450 litres (118.9 US gallons) with a footprint at least 180 cm (70.9 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Rostratus need?
- Rostratus does best at 23–29 °C (73.4–84.2 °F), pH 7.5–8.8 and a general hardness of 8–25 °dGH.
- What group size does a Rostratus need?
- Rostratus is a social species — keep a group of at least 5 so natural behaviour emerges and stress stays low.
- Is the Rostratus suitable for beginners?
- Rostratus sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.