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Re: Belly-sliders
Doug Karpa-Wilson wrote:
>
> IN the course of talking about a sick fish without external symptoms,
> someone mentioned that the fish might have become a belly slider.
>
> What exactly is a belly slider? Is it just a fish that's got a
> developmental problem with its swim bladder, and so can swim properly?
>
A belly-slider is a fish that has a defective swim bladder and is
unable to swim properly, spending most of its time lying on the tank
bottom on its belly, in some extreme cases perhaps even on its side.
Belly-sliders have been the subject of considerable discussion on
KillieTalk in the past so you might find it useful to search the
KillieTalk archives on the topic.
>
> Do they eventually die of this, of just go about scuttling along
> the bottom?
>
Adult fish that become belly sliders can survive quite some time,
especially if kept on their own. However, in a group where the other
fish are healthy, they will generally be picked on and also not be able
to effectively compete for food so invariably die fairly quickly under
such conditions.
>
> How old/big do they need to be before this stops happening? The fish
> in question is around 1" long, so I'd have thought that it wasn't at
> risk anymore.
>
My experience with belly-sliders has been primarily with Nothos. There
are various ways in which belly-sliding can occur:
1. Immediately on hatching, Notho fry will appear to be belly-sliders
but that is quite normal because it takes up to a few hours for their
swim bladders to become inflated and functional.
Under ideal conditions all the fry will be swimming normally within a
few hours of hatching. However, it often happens that some, or in
extreme cases, the entire batch of fry, are not able to attain normal
swim bladder function, remain as belly sliders and generally do not
survive. The reasons for this have been vigorously debated but I don't
think anyone has provided a clear, convincing explanation. Some claim
that it is the result of premature hatching, others suggest excessively
late hatching as the cause. Probably both can cause this condition in
newly-hatched Notho fry. I also think that water quality may play a
role in some cases.
Incidentally, the old idea that the fry need to take a gulp of air at
the surface in order to inflate their swim bladders is not true. There
have been numerous experiments conducted in which the fry were denied
access to the water surface but they developed normal swim bladder
function regardless. It is also doubtful that some of the very small
fry would be capable of overcoming the surface tension and actually
taking in air at the surface.
2. It can happen that juvenile and adult Nothos can become
belly-sliders at some later stage, even after having initially a
normally functioning swim bladder. This will happen most commonly when
the fish are at the sexing out stage but it can affect them at any time
during their lifespan. Again, the specific reasons for this are unclear
but I suspect that bacterial infection may play a role in at least some
cases. This condition is invariably permanent and generally renders the
fish useless.
3. I have also had the experience where Nothos have developed swim
bladder malfunction during shipping. Under such circumstances the
condition can be either permanent or temporary. Here also, the exact
cause is not clear but it probably has something to do with the
pressure changes that the fish might be subjected to as a result of air
transport. When I bring fish back from Africa there are usually one or
two that arrive with swim bladder malfunction and sometimes this
corrects itself within a day or two but in other cases the fish do not
recover. This happens more frequently with very mature specimens than
it does with younger ones.
__________________________________________________
Brian R. Watters
Professor and Head
Department of Geology
University of Regina
Regina, Sask. S4S 0A2, Canada
Tel: (306) 585-4663; Fax: (306) 585-5433
E-mail: Brian.Watters at uregina_ca
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