Sexing Fish

[Notsofab]

Does anybody have any good information or links to information on how to sex fish reliably?

Scooting around the web, I am finding all kinds of information that may or maynot be correct. For example, on one site it said that Serpae Tetra that have the black dot are male while others without the dot are female. On another site it says the dot will fade with age and has nothing to do with sex.

The fish we have in our tank come with aggressive reputations especially when breeding, which is why I'm keen to find a reliable way to distinguish their sex.

I'm particularly concerned about
RAMS
KRIBENSIS
SERPAE TETRA
and ANGELS - though I read that these are nearly impossible to sex until they are mature fish?

Thanks.

 

[chishnfips]

I have had problems sexing fish aswell, I know that with Kribs the male is considerably larger than the female, and the female is more colourful.

as for the other I am not sure.

Also with gouramis it will always be the male that guards and builds the nest.

I have found out that the usual signs of sexing fish has become more difficult because of mixed breeding and it makes it harder to sex the fish.

 

[Inchworm]

Hi Notsofab

I can't help you out with those fish, but it's easy to tell the corys apart. The females are bigger and have rounded ventral fins, while the males are more slender and have smaller and more pointed ventral fins. If you look at them from the top, and if they are mature fish, it's usually not too hard to see the difference.

Here are a pair of my black C. aeneus, for example:

 

[penguinpimp1990]

sicko why would you want to sex your fish? lol just kidding

 

[Notsofab]

I guess it all becomes a little easier in time, once the ladies have matured enough to wear bra's !!!!!

Hi Notsofab

I can't help you out with those fish, but it's easy to tell the corys apart. The females are bigger and have rounded ventral fins, while the males are more slender and have smaller and more pointed ventral fins. If you look at them from the top, and if they are mature fish, it's usually not too hard to see the difference.

Here are a pair of my black C. aeneus, for example:

OK I'm probably being dumb here, but 2 things
1) If you didn't know the age of those fish ( say in a LFS ) then couldn't one just be older and grown larger than the other?
2) Is ventral fin the correct term. i'm trying to get used to the anatomy of fish but keep seeing different terms used. According to this reference its a pectoral fin ? http/floridafisheries.com/Fishes/anatomy.html

 

[Notsofab]

Come on - one of you clever people here must be able to shed some light ???

Anyone ?


*BUMP*

 

[prankster705]

RAMS Mostly by the fact that males usualy have longer fins on the back.
KRIBENSIS Females are wider and bigger
SERPAE TETRA Visually impossible
ANGELS - though I read that these are nearly impossible to sex until they are mature fish? only when mating. Males have a bigger bump between the bottom fins

Hope this helps a little.

 

[sylvia]

Sexing fish depends entirely on the exact species. There is no general rule. Fish are extremely varied creatures.

For the four you said:

RAMS (I assume german blue/gold) - females are deeper-bodied and slightly smaller than males when fully grown - but nothing obvious. Wild-caught males are markedly brighter and have a longer first couple of dorsal rays. However, with all the cultivated fish now available, it's quite difficult to rely on the fins or color to sex them. I find behaviour and body shape far mroe reliable but you need to wait until they are mature. With time and practice you should eventualy be able to tell them apart quite easily.
KRIBENSIS - these are obvious - females have a deep pink belly, males are lighter. Females are also voer-all brighter colored and have more spotting on the upper body (generaly). Males have more blue highlights on the fins and the dorsal and caudal fins of males are much longer and more pointed. the males are also larger over-all and the females look fatter and less streamlined. If you see a male and a female in teh same tank you'll know immediately.
SERPAE TETRAS - Tetras can be rather tricky. With serpaes the only reliable way is probably body shape and fin length. Females are subtly more rounded or 'disc -shaped' and slightly duller in color. The fin length is more a good indication of which fish are deffinately male rather than what each fish is as some males have shorter fins for a lot of their life.
and ANGELS - like you said, these are near impossible tos ex and I've never been able to use any of the suggested methods for sexing even the adult ones. I can only tell if a pair forms and they start breeding. I've heard of all sorts of methods including a difference in head shape which I did try and did not work

 

[prankster705]

^^^Now there you have a complete guide.

 

[sylvia]

About the age thing - you can't tell unless the species involved is one that changes in shape or color significantly as it matures. the only time you'll know for certain when comparing sizes is when they've stopped growing.

As for the fins - most fish have a dorsal fin (the top), a caudal fin (the tail), a pair of pectoral fins (behind the gills on either side of the fish' body), a pair of pelvic fins (also called ventral fins - udnerneath the body near the head) and an anal fin (just before the tail under the body). However, if you take a look at your tetras, for example, you'll notice they have another, very small, fin just before the tail behind the dorsal - this is an 'adipose' fin and only certain fish have it. Other fish, like rainbowfish, actualy have 2 dorsals. Another thing you'll notice is the 'barbels' (whiskers) on your cories and you should be able to see that the anal fin of any of your male livebearers is modified into a tube-like structure. That's called a gonopodium and is used to internaly fertilise the female livebearer's eggs. I don't know how much of that you knew but, seeing as you expressed an interest, I thought I'd mention it

edit: lol - that's twice we posted at the same time

 

[Inchworm]

Hi Notsofab

I can't help you out with those fish, but it's easy to tell the corys apart. The females are bigger and have rounded ventral fins, while the males are more slender and have smaller and more pointed ventral fins. If you look at them from the top, and if they are mature fish, it's usually not too hard to see the difference.

Here are a pair of my black C. aeneus, for example:

OK I'm probably being dumb here, but 2 things
1) If you didn't know the age of those fish ( say in a LFS ) then couldn't one just be older and grown larger than the other?
2) Is ventral fin the correct term. i'm trying to get used to the anatomy of fish but keep seeing different terms used. According to this reference its a pectoral fin ? http/floridafisheries.com/Fishes/anatomy.html
[/quote]

Hi Notsofab

While it is possible for the lfs to have a group of corys with mixed ages, it doesn't usually happen that way because they are raised in fish farms and moved out as a peer group. If they are wild caught, they will usually be mature fish. Even so, with some species it is harder to tell them apart than with others.

If you are buying a group of them and want a certain number of females and males, I suggest buying the biggest fish in the tank. They are usually females. Once they are in a container, look down on them carefully and then look for the males. Don't pick the smallest ones because they could just be slow growing fish and you really don't want them. You want fish that are thinner than the female tankmates. Those are most usually the males.

The pectoral fins are the ones that stick out to the side like you see in the picture above. The ventral fins, sometimes called pelvic fins, are the ones that hang down from the bottom. The female uses them to carry her eggs while she is looking for a place to put them.

Here's a picture of one doing just that:

 

[Synirr]

I can sometimes sex adult angels by looking at them, but I'm not sure exactly what I'm looking at to figure it out
The males are generally larger when fully grown though...