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A. borellii references
Jonathan,
This sounds like an interesting thesis problem. There are some questions you will
have to figure out, however.
1. You say you plan to have 10 fish per tank in a 1:1 sex ratio. A 25 gallon tank
(30X12" bottom?) seems a bit small, but you will certainly see territorial
behavior both in the males and the females.
2. You are interested in "pseudo-female", also called "sneaker males". I doubt
that you will see much of this if you can already sex your fish. Sneaker males
seem to be young males that somehow delay the development of their external
(secondary sexual) masculine features in the presence of dominant territorial
males. If your males already have their masculine features, they can't really
revert, e.g. shrink their finnage - although they may, like the females, not be
highly colorful.
Sexing young fish is always a problem. I have a two year old A. sp. Rotpunkt
sneaker male who looked just like a female in brood dress. I wasn't sure of its
sex until I took out the only "certain" male in the tank. I still got spawns so
unless there was some magical fertilization between tanks, one of the 2 year old
females had to be a sneaker male. Now without any competition this male is
growing larger and developing more masculine traits. Little is really published
on sneaker males. Probably the best discussions are found in the first chapter of
Ingo Koslowski's book "Die Buntbarsche der Neuen Welt - Zwergcichliden" and
section on sneakers in Uwe Römer's "Cichliden Atlas, Band 1".
In regards to biotope studies, I am told that Dr. Wolfgang Staeck did an
excellent job in an article that he published in 1999. I have not seen this paper
but am told that it covers most of your questions on distribution, biotope,
environmental parameters, etc. I am trying to find a copy of it right now. If
anyone can email me a scanned copy I would appreciate it.
Sex determination is well documented in the scientific literature. See if you can
find the following reference: Römer, U. & W. Beisenherz. 1996. Environmental
determination of sex in Apistogramma (Cichlidae) and two other freshwater fishes
(Teleostei). Journal of Fish Biology, v.48, p. 714-725. Not only do temperature
and pH affect sex ratios, but timing of these are important, too.
If you have problems getting any of these (and I imagine you will), contact me
personally off-list and I will supply you with what I have and translations if
needed.
Good luck with your thesis project and have fun!
Mike Wise
jonathan wrote:
> Hi everyone! I was able to convince a professor to fund me in a 25 males/
> 25 females thesis project for my BSc, involving Apistogramma borellii. I
> have 5X 25 gallon tanks, 10 fish in each with a 1:1 sex ratio. I've got
> 5 potting sausers inverted, each with a 1 cm^2 hole, in each tank. I am
> using fine sand, no plants so I can observe the male to male competition.
>
> I am looking for information regarding the nature of
> "pseudo-females" in Apistogramma borellii. Apparently there are males
> which are morphologically similar to females, presumably to avoid
> aggression from the dominant males and perhaps to attain spawning
> opportunities by acheiving proximity. Has anyone seen anything like this?
> I can't seem to distinguish between true females and pseudo-females.
> Any suggestions on reading sources (authors and year)?
>
> Furthermore, I am trying to find info on their natural breeding regime.
> When do they breed (rainseason?) and why? What are the conditions that
> make such a "breeding season" favorable? Any suggestions on reading
> sources (authors/year)? Any thoughts, guesses?
>
> I am also in search of information on the natural temperatures and pH
> values throughout their natural range, throughout their breeding and non
> breeding regimes. I am seeking to investigate their environmental sex
> determination phenomenon (sex ratio of progeny vary with pH and temp). Any
> personal observations in this regard? Any suggested readings? What do most
> people believe the pH and temperatures are, and how they vary throughout
> the year in Apistogramma borellii's range? Anyone know of a good watershed
> database for the range of this species? Anyone know of the definite range
> of this species?
>
> Many thanks,
> Jonathan
>
> -------------------------------------------
> Jonathan Fung... Reef Geek
> Dalhousie University Honours Marine Biology
> Aqua Creations Inc. Assistant Manager
> writer for Marine Fish Monthly
> -------------------------------------------
>
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