How Does One Sex Boesemani Rainbowfish When Juvenile?

[twodoctors]

Hi all,

Got myself 3 boesamani rainbowfishes today. Yes, I know, I need at least 6. And I am planning to get another 3 asap.

Anyway how does one sex them? The LFS couldn't do it, and as it was on offer (3 for £15, which is cheaper than my other LFS), and they had only 3 left, I took them. They have very little colour at the moment. All three have some degree of horizontal banding, but One or two of them are definitely a bit darker. I gathered that the ones with this band is more likely to be female. Is that right? Anything else I should look for when I check on mine/get some new ones? Thanks.

Adrian

 

[Carlovel1]

Hard to sex when juvis but the males may be slightly deeper bodied.

 

[Sanj]

Hi all,

Got myself 3 boesamani rainbowfishes today. Yes, I know, I need at least 6. And I am planning to get another 3 asap.

Anyway how does one sex them? The LFS couldn't do it, and as it was on offer (3 for £15, which is cheaper than my other LFS), and they had only 3 left, I took them. They have very little colour at the moment. All three have some degree of horizontal banding, but One or two of them are definitely a bit darker. I gathered that the ones with this band is more likely to be female. Is that right? Anything else I should look for when I check on mine/get some new ones? Thanks.

Adrian

Hello Adrian,

Melanotaenia boesmani are actually one of the easiest rainbowfish species to sex. I currently have M,boesmani 'Lake Aitinjo' fry, they are about 10-15 mm long and I can already see males developing. Fish you buy in LFS are usually at least 1-1.5" and males should be distinguishable by having definately stronger yellow latter half developing. It is true most mass bred boesamani are comparatively washed out compared to line bred or wild fish, but still you should be seeing dimorphism between the sexes.

I learnt the hard way when i started keeping them 10 years ago and the lfs sold me some boesmani saying the males will colour as they got older. It was not so they sold me all females. While rainbowfish colour up tremendously as they mature, it is nonsense in the case of M.boesmani or G.incisis to not be able to identify them at quite a young age. What often happens is the LFS sells all its more colourful males first and then is left with females.

Here is an example:

Young MALE boesmani

Video from the same stock: Boesmani at an LFS

Are you seeing a definate yellow latter half in the fish? Females have some yellow colouring but it is not distinct as in males and are predominantly olive green. Both have black/dark markings along the lateral line and sometimes smaller horizontal marks.

 

[twodoctors]

Hi all,

Got myself 3 boesamani rainbowfishes today. Yes, I know, I need at least 6. And I am planning to get another 3 asap.

Anyway how does one sex them? The LFS couldn't do it, and as it was on offer (3 for £15, which is cheaper than my other LFS), and they had only 3 left, I took them. They have very little colour at the moment. All three have some degree of horizontal banding, but One or two of them are definitely a bit darker. I gathered that the ones with this band is more likely to be female. Is that right? Anything else I should look for when I check on mine/get some new ones? Thanks.

Adrian

Hello Adrian,

Melanotaenia boesmani are actually one of the easiest rainbowfish species to sex. I currently have M,boesmani 'Lake Aitinjo' fry, they are about 10-15 mm long and I can already see males developing. Fish you buy in LFS are usually at least 1-1.5" and males should be distinguishable by having definately stronger yellow latter half developing. It is true most mass bred boesamani are comparatively washed out compared to line bred or wild fish, but still you should be seeing dimorphism between the sexes.

I learnt the hard way when i started keeping them 10 years ago and the lfs sold me some boesmani saying the males will colour as they got older. It was not so they sold me all females. While rainbowfish colour up tremendously as they mature, it is nonsense in the case of M.boesmani or G.incisis to not be able to identify them at quite a young age. What often happens is the LFS sells all its more colourful males first and then is left with females.

Here is an example:

Young MALE boesmani

Video from the same stock: Boesmani at an LFS

Are you seeing a definate yellow latter half in the fish? Females have some yellow colouring but it is not distinct as in males and are predominantly olive green. Both have black/dark markings along the lateral line and sometimes smaller horizontal marks.

Thanks a lot. That was very helpful.

I managed to get another 3 today from yet another not so LFS. Also £15 for 3. The guy said male are more colourful. So I got 3 which are distinctly more yellow/colourful in the bottom half. At least I know I have 3 males now. I am at work at the moment but I will check them tomorrow. I think I have 3 each, which is not ideal ratio as I understand but nevermind!

Adrian

 

[Sanj]

The ratio is ok. I know breeders who keep a higher ratio of males to females. You dont want to have 5 males to one female, but it is not essential to have females outnumbering males.

 

[drobbyb]

The ratio is ok. I know breeders who keep a higher ratio of males to females. You dont want to have 5 males to one female, but it is not essential to have females outnumbering males.

Actually, that would depend on the fish. Some groups are fine more females than males, but most of the time it isn't. When we recommend more females than males we are recommending something that works 100% of the time, not sometimes, and to a new rainbowfish keeper this should be essential until you learn to read their body language and behavior.

I know people that keep 2 male bettas in the same tank, and they do fine, but I wouldn't recommend you try it

 

[twodoctors]

Out of interest why would I want more male than female for rainbowfish? thanks.

Adrian

 

[drobbyb]

Simply put, the males are more colorful than the females.

 

[Sanj]

Actually, that would depend on the fish. Some groups are fine more females than males, but most of the time it isn't. When we recommend more females than males we are recommending something that works 100% of the time, not sometimes, and to a new rainbowfish keeper this should be essential until you learn to read their body language and behavior.

I know people that keep 2 male bettas in the same tank, and they do fine, but I wouldn't recommend you try it

Granted species to species behaviour can vary as it can down to individuals. There are other factors aswell. Although the Betta comparison is somewhat removed.

I personally do not think this ratio in regard to boesmanis will be a problem as long as the system is a suitable environment to begin with.

However there is a general rule with many fish beyond rainbows and this comes down to dissapating male attentions/boistrousness/aggression towards females. Hence a common 1 Male: 2 females recommendation.