Reproduction in C. kelberi

[channarox]

Channa,
I don't think stunted is the term that I would use, but rather growth retarded is more appropriate. I can see that statement coming back to bite me in the @$$ real fast, so the laughing starts and ends with that sentence
Seriously though, I would not say stunted. Think of it like this: Large Mouth Bass in Florida enjoy a 12-month growing season, while the same species in New Jersey "slow" down in the cooler months. The same is true for C. kelberi in this particular location. Cool?

I have mentioned before that I keep mine cooler than most other people, but I was not sure if I stated how cool....you have a great memory!!!

thanks,
so what youre saying is the retardation in growth benefits the kelberi in that location somehow?
possibly because the availability of larger food items is scarce so they would have to depend on smaller food items?
this means that they do not grow larger because they know that larger food items are harder to find and chasing alot of smaller prey is a waste of energy for such a large fish?

 

[Cichlidgeek]

First of ALL, your questions are really difficult....
Sorry LOL!!

I am scratching my head and trying to do some research at the same time.
I wish I could have done some Ichthyology or Oceanography in college.
No need, you have the answers

" Also, we have to ask ourselves what the number of viable eggs (fecundity) will be at such a small size and young age? Surely they are substantially fewer compared to other, larger females etc...."

I really think the answer replies on kelberi's habitat. If not because there are too many predators... then probably food is scarce. If food is scarce, then each individual should produce less offspring so siblings won't need to compete for food. Well.... the argument can go opposite way, too...shi***...

Read this:
Partitioned spawning stretching over a prolonged period
reduces the competition among larvae, and afterward among
the fingerlings. This type of spawning has previously been
reported for species of Cichla (Fontanelle, 1950; Magalhães
et al., 1996; Câmara et al., 2002; Gomiero & Braga, 2004).

"On the contrary, do they sexually mature at a smaller size/younger age because there is little competition? I pose this side not as the devil's advocate, but because we already know that in many cases where Cichla species have been introduce into resivoirs they tend to become the dominate predatory fish species. So, perhaps it's exactly the opposite than thought?"

My question here will be Do they REALLY mature at younger age?? Or we assume they do because their size ?? see this article... it mentioned about growth of a tiny mouse and big elephant. They follow their own curve, but curve never change.

Read this:
The reproductive biology characteristics of C. kelberi in
Lobo Reservoir indicate that the species is well adapted to its
environment, with high relative condition factor values, a long
reproductive period, large output of fingerlings and fecundity
values near those of other populations established for longer
periods. In this environment the maximum sizes are near those
in other regions where these species occur and the size at
first maturation is smaller for both sexes, probably because of
adaptation to local environmental conditions such as periods of
lower temperatures, which cause a reduction in the growth rate.

Are you using a "temensis" standard looking at "kelberi" as asking why a little mouse mature at tiny size and young age and reproduce so many ??
No, it is never wise to use such a huge beast for a standard

Going back to my pictures finding.... I rarely see any other large fish or predators in Kelberi's habitat ??? correct me if I am wrong please.....
.... compare to amazon river. Maybe at their little size, they are already king of the river PLUS they can't grow much bigger because there are not much larger prey for them to eat and grow bigger.
That depends on the habitat, James. Remember, this thread is only talking about one particular resivoir in one particular state in Brazil
There are many areas where kelberi are found

 

[Cichlidgeek]

thanks,
so what youre saying is the retardation in growth benefits the kelberi in that location somehow?

Impossible to say, but it's interesting to think about. Food for thought

 

[pnoydlyte]

i would think due to the cooler water temps they would mature at smaller sizes because of low hatch rate for their eggs in those tempertures so they would need to spawn more often to get the same amount of offspring in one lifetime compared to warmer temps when they can get the same amount when they start at a larger size

 

[channarox]

IN CAPS

interesting.
we'll have to wait and see.
keep dumping us with more info.
its very interesting really.

 

[Cichlidgeek]

i would think due to the cooler water temps they would mature at smaller sizes because of low hatch rate for their eggs in those tempertures so they would need to spawn more often to get the same amount of offspring in one lifetime compared to warmer temps when they can get the same amount when they start at a larger size

That is an interesting spin on things. I would love to see some form of experiment done that could answer these questions/hypotheses for sure.

 

[Cichlidgeek]

interesting.
we'll have to wait and see.
keep dumping us with more info.
its very interesting really.

Oh, you don't know me well enough my friend...careful what you wish for

 

[Cichlidgeek]

James,
Here is more for you to ponder and sort out. I like torturing you, it's rather fun
Previous studies of the icthyofauna in Lobo Reservoir
demonstrate that after C. kelberi was introduced, at the end
of the 1990s, there was a change in the communities, with a
decline in the relative abundance of some species, such as
Hoplias malabaricus, Geophagus brasiliensis, Astyanax
fasciatus, Cyphocharax modestus and Gymnotus carapo, and
an increase in the relative abundance of the tucunaré (Fragoso
et al., 2005). It is important to stress that once established, it
is extremely difficult to eradicate a species (Lowe-McConnell,
1999). So the implementation of efficient mechanisms to
control this species is necessary to minimize its potentially
harmful effect on the aquatic community.

Here's the funny thing....notice the Hoplias species mentioned above. That is a common wolf fish...a very arrogant and bastardish predator that is capable of swallowing large fishes. BUT.....what is interesting is that juvenile Hoplias do not need to eat their own weight in food daily...unlike all species of Cichla up to about 3 inches or so in order to remain healthy. So, there is a huge number of baby Hoplias that get consumed (based on stomach analysis) compared to a smaller number of Cichla...thus a major offset even between ichthyo-apex predators

 

[pnoydlyte]

oh and another thought...wouldnt cooler water temps intice(sp) spawning in fish like the salmon swimming upstream before winter..infact like animals in general like deer spawning in autumn

 

[Cichlidgeek]

oh and another thought...wouldnt cooler water temps intice(sp) spawning in fish like the salmon swimming upstream before winter..infact like animals in general like deer spawning in autumn

Maybe. In the Amazon region of Brazil, many species of cichlids and other fishes spawn at the onset of the rainy season when water temps actually lower a bit and the water level rises thus flooding the forest and allowing the fry to have access to a broader range of food items and a greater abundance of those same items.