How can you tell if it is a male or female fish?

Question

I have five tiny goldfish (i think they are goldfish but they are about 1.5cm long). The two biggest used to be the same size, but now, all the others have caught up with the smaller of the biggest fish, whereas the biggest fish just keeps getting bigger and fatter!!
S/He is about double the size of all the other fish. He also chases the other fish, and hogs the best hiding spots (under the bridge) and seems to be very greedy. Is it cause it is breeding time, or is it just being a bully??? how can you tell if it's a man or woman??
All teh fish seem to be very happy though, and it has not attacked them, just chases them out of his 'zone'.

Anyways any suggestions would be nice.

By the way I used to call the Big fish "Big Momma" but I don't think I can call it that since it seems she's a He.

Answer 1

The female fish will clean the tank

Answer 2

the serious answer is it depends on the species of fish! Generally males are more colourful, may have fancy tails like the male siamese fighting fish! Females may have a more rounded appearance especially in a live-bearing species.
You really need to find out what fish you have! If they are gold-fish then you shouldn't keep them in anything other than a very large tank or pond. It sound like you may have a group of Platy's and the bigger fish is a male! You should visit an Aquarium stockist or pet-shop and see if you can find them there. Take a photo of the fish and post it on the here and ask people to identify it. (I don't know how you do it though) or visit one of the many fish-keeping sites and look in the data bases, search tropical fish keeping for a list.Good luck finding out what they are!

Answer 3

This will be useless unless the fish are at least a year old.

The only way you can learn to spot male and female goldfish is by closely observing known males and females and noticing their various traits. A pet shop could be a nice place to learn this.
BUT you could also look out for these signs :

1. Midline ridge: male goldfish have a ridge running through the back of pelvic fins to their vent opening on the underside. The ridge is either completely missing or smaller in females.

2. Firmness of abdomen: The area between pelvic and anal fins is pliable for females but very firm for males.

3. Shape of the vent: Though difficult to figure out, the female vent is rounder and convex, whereas the male vent is thinner and concave.

4. Shape of the pectoral fins: Male pectoral fins are pointed with stiffer leading ray and female pectorals are rounded, shorter with finer front fin ray.

5. Features: females are brighter colored and are more active. This could be a difficult way of pointing out a female but you could try!

6. Check out: One theory says that you can introduce a known female into the tank and watch for the reaction of fish. Males will check out the new fish but the females will show no interest!

Good luck :]

Answer 4

Judging by your other post, your fish are too young for breeding behavior. You need to get them out of that 2 gallon tank and into a 55 gallon. If they keep growing they will produce so much ammonia that your water will be toxic daily, if they stop growing their organs will continue and they will die.
What do you mean the best hiding spots? Goldfish should be active and on the move constantly. They should not have hiding spots. Listless goldfish is a sign of serious problems with water quality or sickness.

Answer 5

For gold fish, some of the observations you can make or

1. Find who is chasing who?. Normally males chase females all the time.
2. Females are bigger in size than males.
3. Males have stiff finrays. Females have round shaped pectorals.
4. During the spawning time, male fish develop white dots on their gills.

Answer 6

It is very difficult to sex goldfish, as they are gold and have no defining markings and are community fish. Generally the dorsal fins are different with the male having a slight V shape in them whilst the females fins are straight. However, this is of no use if you have all males or all females as you will have no comparison.

Answer 7

My answer to the question is that the fish is a male fish because of the following reasons;
* Because male fishes are always bully
* Because male fishes usually grow fatter, bigger and stronger than female fishes
* Because male fishes are stronger than female fishes
* Because the external features of male fishes are stronger than the external features of female fishes, like the nature of the external fines, gills, etc.
* Because the male fishes always fight for mates

Answer 8

The detials about the fins rigidness is good.

Lisa isn't necessarily right. Human females are much more pleasing to the eye than human males. A few other animals follow our trend too.

Answer 9

I learned in science, and biology that the male species of anything is more colorful & pretty than the females so maybe that might help, other than going by that I have no clue how you would tell from a fish. Ask a vet...

Answer 10

your fish is being teratorial all fish are like that they like there own spaces and yes he cud be making a space to mate best way to tell what sex a fish is is by its dorsal fin males are usualy more pointed than the females .if he start attacking the others it wud be best to move him to another tank