Checklist of interstitial fishes
In addition to fishes which inhabit the relatively large conduits of caves (which by definition are enterable by humans), and those in the relativley small conduits of groundwater aquifers, there is another group which live substantially, or obligately, in the sediments on the beds of rivers or in marine sands. Many of these fishes develope some degree of troglomorphy, as a result of life in darkness, and can thus legitimately be considered as subterranean fishes. The habitat has several names including the interstitial, the psammophillic ("sand loving") and the meiobenthos. We will here use the first of these names. Although no vertebrates are mentioned within it the most critical source for this habitat is Giere (2009). Other valuable sources are Rundle, Robertson and Schmid-Araya (2002), Higgins and Thiel (1988), Heip (1984), Shields and Malcolm (2009) and Wood, Hannah and Sadler (2007). Schmid and Schmid-Araya (2002) discuss the value of invertebrate meiofauna as food for fishes and this is clearly of importance to permanently interstitial fishes. The International Association of Meiobenthology have a useful website.
As currently understood two subfamilies of the Trichomycteridae with 22 species (all in freshwater), one genus of Gobiidae with 14 species and one species of Gobiesocidae, with 5 species, (all marine) have permanently interstitial representatives. Both of the marine genera have remakable adaptations to the spine to allow them easier access to the restricted environment (Luciogobius - Yamada et al. 2009, Gouania - Wagner et al. 2019, Wagner et al. 2020).
Species accounts for all of the interstitial fishes have yet to be written but will be written as time allows.
Order: Siluriformes (22 species)
Suborder: Loricarioidei (22 species)
Family: Trichomycteridae (22 species)
Sub Family: Glanapteryginae (11 species)
Sub Family: Sarcoglanidinae (11 species)
Order: Gobiiformes (14 species)
Suborder: Gobioidei (14 species)
Family: Gobiidae (14 species)
Order: Gobiesociformes (5 species)
Suborder: Gobiesociformes (5 species)
Family: Gobiesocidae (5 species)
Lepadogaster pigerGouania prototypusRupisuga nicensisLeptopterygius coccoi
Lepadogaster pigerGouania prototypusGouania pigerLeptopterygius piger