F1 Pelvicachromis pulcher

[Andre]

Hi There

My F1 P. pulcher are starting to colour up nicely.

They have been fed mainly spirulina based tablets and lots of different kinds of frozen shrimp.

A bit overkill for kribs maybe, but the results are worth it IMO.

These little ones are around 5cm and actually do the gill flare when displaying to each other. I have not seen this behaviour in kribs before.

 

[tjudy]

Cool... do you have any females? I will try to post some pictures of my wild female that is guarding fry... awesome colors.

 

[Andre]

Hi Ted

I have a few but they are not displaying quite yet. Mine are mostly males because of the slightly higher pH in the tank.

Luckily I have a friend with very low pH water and some very nice yellow kribs. We will be swopping males for females pretty soon.

 

[retro_gk]

That's interesting, Andre. I have very hard water here and I get close to 70% females, both with an F1 pair and an aquarium strain.

 

[tjudy]

Hardness is not necesarily the issue Rahul... what is the pH? Conductivity (TDS) will not make a difference. KH will not matter either, except in the extent to which it affects the pH. I know of plant tanks that use carbon dioxide injection that have a KH in the range of 6 - 8, but teh CO2 keeps the pH down near 7 or slightly under.

I am trying to talk a few people with the tank space and time to grow out a lot of kribs to try to solve the pH/sex ration issue. Generally speaking a pH above 7.2 should generate more males and below 6.8 more females. I keep my fish within that range and get a good ratio.

 

[tjudy]

Here is one of my wild females.

 

[retro_gk]

Ted, last time I checked, pH was around 8.

I think temperature factors in as well... lower temperatures (20-24C) producing more males and higher (28-30C) producing more females. My tanks are at 26C.

I do get more even ratios with other dwarfs (Apistogramma, Nannacara etc) but, I also use softer/more acidic water with them. The one time I did use RO with my kribs, I lost all the fry to an accident. I must try that again sometime before I can make any conclusions.

One thing I have considered briefly is that certain populations/strains of fish may be genetically predisposed to skewed ratios. Thoughts on this?

 

[tjudy]

Fish gender is not determined by chromosomal inheritance like it is in humans (and other creatures like fruit flies). There is definitely a possibility that sex in kribs is associated with allele inheritance, and therefore I guess it would be possible to create a strain of fish that produce heavily to one side or the other through inbreeding.

 

[Andre]

Hi Ted

My pH is 7.4. I have probably 70% males.

My friend's pH is 6, sometimes lower and VERY soft. He is lucky in that the water is like that out of the tap. He has practically no males.

I can try help you in the experiment if you would like. I have a spare 2 footer that I can use