Spathodus

Genus Overview: Spathodus (Spatula-Teeth Gobies)

The genus Spathodus represents a highly specialized, behaviourally fascinating, and morphologically extreme branch of cichlids endemic to Lake Tanganyika. Settled within the small, wave-loving Eretmodini tribe, these specialized "Goby Cichlids" share the extreme upper shallow waters of the lake, adapting perfectly to colonize the violent, heavily oxygenated surf and surge zones.

Swim Bladder Reduction & Outward Chisel Dentition

The name Spathodus translates from Greek to imply "spatula or blade-like tooth," calling out their most critical taxonomic trademark. To survive in shallow, crashing coastlines where regular fish would be violently tossed against the rocks, they have completely **fused and reduced their swim bladders**. Lacking internal buoyancy, they sit directly flat on top of the boulders, hopping, skipping, and skipping from stone to stone exactly like marine blennies.

While they occupy the exact same wave-swept biotope as Eretmodus, they avoid direct food competition by developing completely different mouth parts. Spathodus possess a series of long, single-pointed, and exceptionally narrow unicuspid chisel teeth that protrude directly outward from their lower jawline.

Instead of flatly shearing down broad algae filaments, they use these protruding blade teeth like a tiny scraper or comb, cleanly sweeping through the Aufwuchs (algal carpets) to precisely extract hidden micro-invertebrates, insect larvae, and loose single-celled diatoms.

Valid Species Directory

Modern scientific records recognize two valid species within this specialized grazing lineage, featuring a massive size contrast:

• Spathodus erythrodon Boulenger, 1900 – The absolute historical type species of the genus, commonly called the Blue-Spotted Goby Cichlid. Features a highly manageable dwarf profile decorated with dozens of glittering, neon-blue iridescent spots lining its head.
• Spathodus marlieri Poll, 1950 – Marlier's Goby Cichlid. A massive, highly robust giant of the tribe that can grow nearly double the size of its sister species, preferring highly turbulent rock-shores.

Aquarium Husbandry & Advanced Mouthbrooding

Adult lengths vary heavily, running from a compact 3.5 inches (9 cm) in S. erythrodon up to a substantial 6 inches (15 cm) in large males of S. marlieri. They can be safely kept in 40 to 75-gallon aquariums. To satisfy their surge instincts, provide an absolute abundance of stacked, flat rocks and smooth river stones forming low matrices, combined with heavy-duty wavemakers and massive surface air stones to maximize internal oxygenation. Coarse gravel must be avoided to protect their mouthparts.

Reprodutively, they exhibit an incredibly advanced, fascinating strategy known as **delayed maternal mouthbrooding** or **bi-parental mouthbrooding** depending on the specific island population. A bonded pair will spawn on a flat rock, and the female carries the eggs inside her mouth for roughly two weeks. In many northern variations, she will then transfer the developed larvae directly over to the male cichlid, who shares the mouthbrooding burden until they are ready to emerge as fully independent fry.

Because their digestive tracts are intricately long to process high-fiber wild roughage, their captive diet requires extreme precision. They must be fed a strictly herbivorous diet high in premium spirulina flakes and vegetable matter. High-protein or fatty mammal meats will break down their lengthy systems, triggering fatal intestinal blocks known as "Tanganyikan Bloat."