Mouthbrooder

However, [Franz] Steindachner (1875), in describing Arius planiceps, a catfish from Panama, found that at the breeding season the innermost edges of the ventral fins of the female are developed so as to form a kind of pocket. He conjectured that the eggs are extruded into this, fertilized by the male, and then taken into his mouth. He found a similar structure on the female of A. kessleri, the male of which is also a mouth brooder.

Mozambique mouthbrooders are native to coastal streams of southeast Africa, especially the Zambesi River, Mozambique.

In almost all mouthbrooders, guarding the young is undertaken by the female (uniparental maternal family) though the male may participate exceptionally, notably in S. mossambicus [...] In S. galilaeus [...] and S. multifasciatus [...] the two sexes form a stable couple and both practice mouthbrooding. This seems, therefore, to be an intermediate stage between the biparental family of substrate-spawners and the uniparental family of mouthbrooders [...].

The very small Tanganicodus irsacae is a typical biparental mouthbrooder that collects eggs immediately upon deposition and retains them in the buccal cavity for about 14 days at which time fully formed young 11mm long are released and begin oral feeding.

[A]lmost all mouthbrooding species are found in Africa, and many are restricted to one of the African Great Lakes. Among the few exceptions are Sarotherodon melanotheron, a paternal mouthbrooder which is widely distributed in West African rivers and estuaries, and S. galilaeus, a biparental mouthbrooder with an even broader distribution across North-central Africa [...].

The cardinalfishes are interesting in their reproductive biology. They are mouthbrooders, in that the eggs are held, usually in the mouth of the male, until hatching; this is one of the only marine fish families to reproduce in this way.