Rare cave fish - Clarias cavernicola

Discussion in 'Advanced Topics' started by Hendre, Jun 30, 2020 at 11:05 PM.

  1. Hendre

    Hendre Polypterus freak

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    Preface - I wrote this for the main forum I inhabit, but thought it is worth sharing some information on local fish.

    Hey everyone.

    In my routine fit of Ichthyological madness I have decided to do more research on an unusual species of catfish from Namibia, next door to me. The Spelonk baber, or cave catfish, formally named Clarias cavernicola due to it's subterranean habitat, is a small catfish species that inhabits a single cave system in the North of Namibia. If you travel about 220 miles North from Windhoek you will end up at the Dragons breath cave wherein our little curiosities live.
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    Clarias cavernicola is small, commonly reaching 130-155mm TL, significantly smaller than the sharptooth catfish (Clarias gariepinnus) that is often seen in fishing or fish tanks. Not much is known about the life habits of these fish due to the difficulty of accessing their habitat deep in the caves. They mainly inhabit a large pool with a surface area of 45 square meters, and a depth of 100m, that has been mapped so far. The catfish mostly inhabit the top 3 meters of this pool where oxygen concentrations are highest, unusually their atmospheric breathing apparatus is reduced compared to other Clarias species, and are rarely seen gulping for air. The reason why they developed this way is still not confirmed but it is possible that the cave water has higher oxygen levels than some of the swampy waters their cousins inhabit.

    As far as diet goes they appear to be scavengers, having been found with bat guano, cave insect exoskeletons, moths (possibly from bats) and other invertebrates in their digestive system. There is little evidence that they hunt their own prey, and with reduced olifactory senses seem to rely on their barbels to find food. It is suggested that the bat guano provides most of their nutrition. As with most cave dwelling fish, their eyes have recessed and do not have any function.

    Through surveys the total population in the main pond is estimated to be about 120 individuals, but the discovery of several smaller pools in the cave system has yielded more fish and thus the population is said to be around 200 fish. This was a recent find, with the last full survey done in 2019. So far any attempts at captive breeding have failed to produce any offspring, although the presence of small fish around 4cm in size suggests that breeding is ongoing inside the cave. I have not heard of any attempts since 1995 so it may be possible in future. As far as conservation goes, the catfish is well protected by its cave system, and the owner of the land is conscious of the value of these fish which is a blessing, he only allows permitted groups to visit the cave. A large threat is ground water extraction, dropping water levels in the cave, but this has been heavily reduced in recent years. Climate change does unfortunately bring new risks which will have to be monitored closely.

    This is just a brief summary I could make from information available. The rarity of cave-dwelling fish in Africa (8 in total) makes these little catfish even more rare and interesting! I sourced most of the information from this article: https://n-c-e.org/sites/default/files/2019-12/Final_report_Clarias cavernicola_November_2019.pdf

    I may well end up doing research on these one day, at least that's the dream. Hope you enjoyed the short read!
     
    Cale24, T. Guppy, ZubairKhan and 4 others like this.
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  3. T. Guppy

    T. Guppy

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    Very interesting! Thanks for sharing :thumbup:
     
  4. Saibot

    Saibot

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    Cool looking fish
     
  5. OP
    Hendre

    Hendre Polypterus freak

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    They're most unusual. It's a shame there are not many other tiny clarias species like this :(
     
  6. RABUBI

    RABUBI

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  7. SalmonAfrica

    SalmonAfrica Batfish

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    Or rather, they exist but aren't traded often. Quite a few smaller members in the family.

    This has been something that's been popping up as a field with great potential to dig into. In the past decade or two so many cave dwelling fish have been discovered, primarily in Asia. The fact that Africa has so few cave species may likely have to do with a lack of exploration, than an actual lack of diversity. I guess that remains to be seen. However, we do have a bunch of cave species-like forms dwelling in the deeper parts of the Congo, as well as some species displaying similar adaptations for living in interstitial spaces in the substrate of rivers and lakes. I'm sure we'll be seeing a lot more interesting stuff in the near future!
     
    Hendre and T. Guppy like this.

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