Cetostoma regani (Zugmayer 1914, 24cm) is the deep sea pink flabby whalefish, a relative of the shallow sea snakehead Channa.

According to Johnson et al 2009, "We resolve a long-standing biological and taxonomic conundrum by documenting the most extreme example of ontogenetic metamorphoses
and sexual dimorphism in vertebrates. Based on morphology and mitogenomic
sequence data, we show that fishes currently assigned to three families with greatly differing morphologies, Mirapinnidae (tapetails), Megalomycteridae (bignose fishes) and Cetomimidae (whalefishes), are larvae, males and females, respectively, of a single family Cetomimidae. Morphological transformations involve dramatic changes in the skeleton, most spectacularly in the head, and are correlated with distinctly different feeding mechanisms. Larvae have small, upturned mouths and gorge on copepods. Females have huge gapes with long, horizontal jaws and specialized gill arches allowing them to capture larger prey. Males cease feeding, lose their stomach and oesophagus, and apparently convert the energy from the bolus of copepods found in all transforming males to a massive liver that supports them throughout adult life."

Aenigmachanna gollum (Britz et al. 2020) is newly discovered dragon snakehead, a cave fish. The cheekbone (light tan) is a large lacrimal, not a maxilla, with unique twin dorsal processes. Note the twin postfrontals, typical of primitive fish, though typically not as developed as here. The actual maxilla (green) is a vestige.

Symbranchus marmoratus (Bloch 1795; 50–150cm) is the extant marbled swamp eel. The dorsal and anal fins are vestiges. Other fins are absent. This eel nests with Aenigmachanna in the LRT. It lives on land in tunnels and underwater. Some females transition to males. Males guard the nest.

Monopterus luticolus (Britz et al. 2016; 20 cm in length) is an extant species of swamp eel close to Synbranchus (above). This species is the first from Africa. Others are from Asia. Note the tiny blind eyes and single ventral gill opening. No fins are present on the adult. In life the color is deep magenta.

Britz et al. report, "Several species are known for their burrowing, amphibious life-style and their ability to survive outside of water due to the possession of highly vascularized secondary air-breathing organs accompanied by substantial changes to their vasculatory systems."

"There is no clear discontinuity in structure between abdominal and caudal vertebrae in synbranchids."