Reproduction in C. kelberi

[Cichlidgeek]

While reading through a paper on the reproduction of C. kelberi, I found the following statement:

The size at first maturation estimated for Cichla kelberi in Lobo Reservoir (Sao Paulo, Brazil) for females and males was 20.7 (8.1 inches) and 21.5 (8.5 inches) cm in total length, respectively.

What do you guys think of this?

 

[X-Tank]

In an environment without natural predators, reptiles and birds grow larger and larger,
ie: Raphus cucullatus ( Do Do Bird ) from Indian Ocean island of Mauritius, Or
Varanus komodoensis ( komodo dragon ) from islands of Komodo, Rinca, Flores, and Gili Motang in Indonesia.

In the opposite... species tend to grow smaller and mature at smaller size in order to breed faster before get eaten.

Not sure what kind of habitat kelberi are in. What are their natural predators???
Is there a reason forcing them to breed at such smaller size compared to other Cichla species... ??

just my thought.

 

[Cichlidgeek]

In an environment without natural predators, reptiles and birds grow larger and larger,
ie: Raphus cucullatus ( Do Do Bird ) from Indian Ocean island of Mauritius, Or
Varanus komodoensis ( komodo dragon ) from islands of Komodo, Rinca, Flores, and Gili Motang in Indonesia.

In the opposite... species tend to grow smaller and mature at smaller size in order to breed faster before get eaten.

Not sure what kind of habitat kelberi are in. What are their natural predators???
Is there a reason forcing them to breed at such smaller size compared to other Cichla species... ??

just my thought.

Good thought....and you pose a good question. What factors contribute to such a low reproductive age/size class compared to other Cichla species? 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....


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? See below:

Some works have evaluated the effects of introducing of Cichla sp. in native communities. In Panama, the dispersion of Cichla ocellaris in the area of the Chagres River led to the disappearance of many native fish species, as well as zooplankton, insects and piscivorous birds, simplifying the food chain (Zaret & Paine, 1973). Godinho et al. (1994), comparing the icthyofauna of the lakes in the Rio Doce Valley in Minas Gerais, Brazil, reported that small fish species disappeared from lakes colonized by Cichla ocellaris.

Note that C. ocellaris = C. kelberi here.

 

[channarox]

interesting read....
heres my take....
i think they do mature at a much smaller size than other species given their smaller max size.
however,i think the age at which they are sexually mature would still be the same as say,a mono.
this being said,they would have to grow slower than most species for what i said to be possible.
being that it would take them the same number of years as other species to reach a smalerl breeding size.
just my opinion.
the reasons behind their slower growth,smaller size,etc. etc. i cannot comment on.
although i do think that it is possible that they do not grow to a larger size because they have no competition or predators.

 

[Cichlidgeek]

interesting read....
heres my take....
i think they do mature at a much smaller size than other species given their smaller max size.
however,i think the age at which they are sexually mature would still be the same as say,a mono.
this being said,they would have to grow slower than most species for what i said to be possible.
being that it would take them the same number of years as other species to reach a smalerl breeding size.
just my opinion.
the reasons behind their slower growth,smaller size,etc. etc. i cannot comment on.
although i do think that it is possible that they do not grow to a larger size because they have no competition or predators.

I understand what you're saying, but have a look at this:
The differences in size at first maturation can also be related to external factors. In Lobo Reservoir juveniles experience a period of low temperatures in the winter, that can retard growth. This pressure does not occur in places where the temperature variations are smaller, such as the Brazilian Northeast, where after completing one year of life, the age of first maturity of Cichla ocellaris (Zaret, 1980), the individuals have reached greater lengths.

Interesting....so they can take cooler temps, too

What I have not told many of you is that I am growing mine out in water that is barely 80F and still getting an inch a month growth from them so far. Two of my (males?) are almost 5 inches TL now

Also, have a look at this statement:
In Lobo Reservoir, Cichla kelberi males and females reach similar maximum lengths. The same observation has been made in some other places where Cichla species have been studied (Jepsen et al., 1999; Câmara et al., 2002; hellapa et al., 2003). In Volta Grande Reservoir in Minas Gerais, C. monoculus males and females attained similar lengths, while C. ocellaris males were larger than the females (Gomiero & Braga, 2003).

Interesting in that we may not see such a size difference between males and females where in "all" other species there is a significant size difference between sexes. So, maybe my "big ones" are a pair...not two males? We shall see

 

[channarox]

I understand what you're saying, but have a look at this:
The differences in size at first maturation can also be related to external factors. In Lobo Reservoir juveniles experience a period of low temperatures in the winter, that can retard growth. This pressure does not occur in places where the temperature variations are smaller, such as the Brazilian Northeast, where after completing one year of life, the age of first maturity of Cichla ocellaris (Zaret, 1980), the individuals have reached greater lengths.

so what its saying is that the reason for a smaller size when reaching sexual maturity is that growth had been stunted when younger?
and those that are not exposed to this kind of stunting are capable of reaching a larger size at sexual maturity although both are at the same age?

Interesting....so they can take cooler temps, too

What I have not told many of you is that I am growing mine out in water that is barely 80F and still getting an inch a month growth from them so far. Two of my (males?) are almost 5 inches TL now

i think you mentioned that in a thread before...
the paragraph in blue states that the colder temperatures causes stunting correct?
however your juveniles still continue to grow quickly even in colder water.

in red.

 

[channarox]

Also, have a look at this statement:
In Lobo Reservoir, Cichla kelberi males and females reach similar maximum lengths. The same observation has been made in some other places where Cichla species have been studied (Jepsen et al., 1999; Câmara et al., 2002; hellapa et al., 2003). In Volta Grande Reservoir in Minas Gerais, C. monoculus males and females attained similar lengths, while C. ocellaris males were larger than the females (Gomiero & Braga, 2003).

Interesting in that we may not see such a size difference between males and females where in "all" other species there is a significant size difference between sexes. So, maybe my "big ones" are a pair...not two males? We shall see

youve got me confused now...
so in some species there is significant differences in eventual size in the sexes and in other species eventual size is the same?

you say your "big ones".
are you referring to the kelberi you are growing out?

 

[X-Tank]

First of ALL, your questions are really difficult....
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.

" 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 relies 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...*****... ( In contrast to abundant predatory environment... animals need to produce a lot in order to have few survive and pass on the offspring...ie sea lobster and octopus. ) Am I confusing everyone and myself... yes
okok....

No predator + abundant food = grow large and mature slow
A lot of predators + abundant food = grow large and mature fast
No predator + no food = grow small and mature slow.
A lot of predators + no food = grow small and mature fast.

IMO

"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.

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 ??

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.

 

[Cichlidgeek]

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!!!

 

[Cichlidgeek]

youve got me confused now...
so in some species there is significant differences in eventual size in the sexes and in other species eventual size is the same?
ACCORDING TO THIS PAPER YES, I AM JUST PASSING ALONG INFO FOR US TO TALK ABOUT. I AM NOT DICTATING ANYTHING
you say your "big ones".
are you referring to the kelberi you are growing out?
YES

IN CAPS