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RE: N. fuscotaeniatus
"RJ" (whoever that may be ?) wrote:
>
> To Brian Watters and others who have been there:
>
> Some years ago I saw a TV program on Africa. They indicated that when the
> rains come, first, a small crustacian hatches in vast numbers. Then the
> small annual fish hatch feasting on the shrimp. Could you possable tell us
> if this is true? Is there a super abundant fresh water shrimp
> which hatches
> first and provides the food source for the Nothos? If you have
> encountered
> these shrimp can you tell us something about them?
>
Yes, I have encountered these freshwater shrimp on many occasions and their
presence in a pool can almost always be correlated with an absence of Nothos
(and other fish, for that matter). I suppose one could argue that the reason
we don't find them in pools where Nothos occur is because the Nothos (and
other fish) eat them. While I am sure they do eat them, I would say that
these would constitute only a small part of their diet; there must be many
other aquatic (and non-aquatic) organisms that the Nothos, both fry and
adults, eat.
>
> Also if you have had the oppertunity to read my questions about
> Notho-Fade-Away. The condition where the Nothos stop eating and will never
> eat again. Could there be any circumstance where this may be some kind of
> adaptive behavior in the wild?
>
> As I have lost FUS to this condition, have
> you seen it among any of the wild specimens you collected or in early
> generations?
>
I am not exactly sure what you mean by "adaptive behavior in the wild" but,
no, I have never seen evidence of Nothos "fading away" in the wild. Usually,
Nothos in the wild are plump and healthy regardless of their age, the
population density and how close their pool is to drying up. I have seen and
photographed perfectly healthy and well-fed Nothos flopping about in so
little water that they were on their sides (as their habitat was in the
terminal stages of drying up). I have seen locations with incredibly high
population densities with perfectly healthy fish. For example, one locality
I collected from in Malawi was a shallow pool (30 cm maximum depth) with an
area probably of no more than 200-300 sq. m. and every sweep of the seine
yielded literally hundreds of fully grown (3 inch plus) Nothos all in superb
condition. Where the food came from to maintain so many fish in such
condition I have no idea.
The only times I can remember finding Nothos in poor condition (i.e.
somewhat emaciated) was where their population density was high AND there
was a high density of OTHER types of fish in the same pool. Clearly, this is
a result of competition for a limited supply of food. When Nothos are the
only fish present in a pool the population seems to be able to adjust in
size according to the amount of food available. However, this is pure
speculation on my part.
>
> Do you perhapse know how to get them to start eating again?
>
No, I don't. I have had batches of Nothos stop eating and die off but it
doesn't happen often enough to be a concern to me. When it does happen it is
usually when the fish are old and not producing many eggs anymore so it is
not something I worry about.
>
> Lastly I would be very interested to know, in the matter of FUS,
> when is the pool flooded and when is it dry.
>
This is difficult to say because, in detail at least, it would vary from
year to year. That is what makes collecting Nothos so unpredictable, one can
return to the same locality in successive years at the same time of the year
and find them with water one year and dry the next. However, in general, it
would be determined by the seasonal rainfall pattern in the coastal part of
Tanzania. For this region the main rains start in November and end in May.
However, because the early rains are sporadic, many localities may not
actually have Nothos in them until about March. Some pools during some years
will be dry by early June, others may contain water until late July. When it
comes to collecting, as the saying goes, "You pay your money and you take
your chances".
___________________________________________
Brian R. Watters
University of Regina
Regina, Sask. S4S 0A2, Canada
Ph: (306) 584-9161 (home); (306) 585-4663 (work)
Fax: (306) 585-5433
E-mail: bwatters at sk_sympatico.ca
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