Gender Determination in Juvenile Freshwater Angelfish

The only sure way to distinguish the gender of a freshwater angelfish is to observe their spawning equipment, which doesn’t get deployed until they’re ready to spawn. Before that, you can make some educated guesses based on physical features.

Although there are no hard rules, female angelfish are usually smaller than males. If you want a pair and plan to buy some juveniles, pick three larger fish and three smaller ones.

In several months when the angelfish are close to adult size, the females will become gravid. When they are swimming toward you, look between the ventral (bottom) fins. The females will usually have a larger tummy than the males.

The third way to make an educated guess is to draw an imaginary line vertically near the gill plate to the top of their head. Now look from that line to their upper lip. Females usually have a straight forehead, and males have a forehead that drops just above the eye then continues fairly straight to the upper lip. They call that kind of description anthropomorphism (corrected to “sexual dimorphism“) but I thought it would be easier to understand than a bunch of Latin words I don’t know.

Image posted by Brett

So... what do you think? Please leave me a comment.

Johnarthur is a veteran at My Aquarium Club.

36 Comments:

  • admin: With six fish there is very little chance to get only one gender - that’s a good rule of thumb to use on any plan for pairing... Good point.
  • admin: Added an image :-)
  • johnarthur: That’s one beautiful photograph. Although they are altum angelfish (I think), the bump in the forehead illustrates one way to distinguish a male angelfish. The bump is not so prominent in the more common angelfish.
  • angela_brown: Unfortunate but true.
    I have noticed that the bump is easier to see in silver angels... Which I’m guessing are the closest that I have to Altums. I don’t ever see me having the money, time, or patience for Altums...
    The large smokey that I have the bump is almost non existant. It would be very handy for me if all the males had bumps...
    Lizel passed on a week ago, and I need to find another female for Mac Daddy... I have 4 that are at 10 months, but I’m just not sure of their gender. I need that pair... so... I guess I’m just going to put them all in there and hope for the best... Maybe I can get a pair without them killing each other...
  • emil: i have a baby angel fish and i want to get him a female so they would breed. but how long would that take hes realy small
  • johnarthur: Growth rate depends on water conditions and types of food. Angelfish like 82 degree water and a varied diet that includes some frozen foods like brine shrimp (baby size for little ones, adult size for mature ones). They reach spawning condition in six months to a year; close to a year is more common. As mentioned above, if you have six angelfish there is a very good chance you will have at least one pair. The males tend to be larger, so if you buy some from an aquarium shop, make sure to get mixed sizes.
  • achintya: nice one...
  • kevin: what can i do to encourage my angels to spawn?
    I have 9 fish in a 5 foot tank.
    5 of the fish are of breeding age, the other four are juveniles.
  • johnarthur: Sometimes, a partial water change will trigger spawning, as will raising the temperature a little or feeding some live food. The more exotic types of angelfish can be reluctant to spawn and may never do so. The best chance is a group of juveniles of similar age. A spawning pair will need an aquarium to themselves.
  • sombuddha: Hi! John this was a great article by you.Please can you be a bit illustrative on the imaginary line part.
    Hope that will help a lot.
  • radar: is it luck when i bred mine. I got 8 angels about the size of quater. After awhile 4 paired off. it seemed one pair was the alpha pair and was the beta pair n tank. both pair layed eggs. ? i read that angelfish where all born female. like largemouth bass. and then changed their sex when mature. U the angel man John any truth to this.
  • johnarthur: I know that we humus beans all start out as females and will continue to be females unless a certain genetic instruction is sent. It happens automatically sometime during the gestation period. The process may be similar for all creatures. I’ve read about and seen a few live bearing fish change gender but never an angelfish. Of course, you can’t distinguish gender for positive until they spawn.
  • Cindy: Ok, I had 6 angelfish and one of them died two days ago. Now the other 5 are picking on each other. Is this normal? I believe it could be because of the change in pecking order but I also have no idea about the sex of them and wondering if pairing and spawning could be the issue. I have pictures of them. Maybe someone could take a look and give me educated guess on their sexes??? Thanks for the help.
  • ampnave: wow, those are beautiful angelfish. what kind are they? where would i get them? Those are some of the most beautiful angels i have seen!!!!!
  • johnarthur: They are called Altum angelfish and are native to a very small habitat. They grow larger than the more common angelfish and are fairly difficult to keep. In the last few years, more altums have been available, but some people think they’re hybrids. Altums are beautiful fish for anyone with a really large aquarium and lots of patience.
  • ampnave: Hello johnarthur, i have the one 55 gallon aquarium with 17 fish, three being angels.
    I have a 36 gallon bowfront coming and have decided i want angels only.
    When you say large aquarium, is 36 gallons large enough for 6 or so angels? (and 4 cory’s)?
    I would be happy to pay for your help if any of the above questions are a yes, if not, it sounds like
    i need to reconsider. Thank you
  • FrootyKakes: Great advice!! Thank you for sharing your knowledge with us! I find it both educational and helpful :)
  • FishDaddy: Thanks for the post as this will help to see if I have a pair that may mate or just be mates.
  • lisa: I’ve got 3 angels,one is rather large,other 2 medium. I didn’t know sex of any of them,until this evening,the large one laid eggs,on side of filter,then one of the medium,ate them all,so disappointed,water,and tank all good,so,how do i stop this happening again,and care for angels,and eggs? Never had this before,after years of fishkeeping! Thankyou.
  • johnarthur: For starters, the spawning pair needs its own private aquarium of ample size. In a community tank, the eggs will always get eaten.
  • Lisa: Thankyou very much,i have 2 spare Tanks,and i have discovered the pair,by observing their behaviour,so,i will get right onto that. Thanks johnarthur. Much Appreciated. Lisa.
  • Tasha: If that’s the case, i’m confused! My female is the one with the bumped head. I only know this because I watched her lay the eggs this morning. I also noticed her "part" was wider and longer than of the other fish which was smaller and not as thick. I assume the smaller was the male see as how nothing was laid as it passed over the eggs. Am I crazy?? lol help!
  • Taryn: Is it possible for freshwater angel fish to change genders?
  • jazza: I can’t really tell if my angels are mature any advise?
  • Brenda: How can you tell female from male angelfish
  • thea: @Brenda–that is precisely what this entire blog is about. JA says it’s impossible to be sure unless they are spawning but you can make some educated guesses and then lists them.
  • boo boo: Does The Male Angelfish Get The Female Angelfish Pregnant Yes/No
  • thea:

    @booboo. Angelfish lay eggs so they do not get “pregnant” but males do fertilize the eggs externally by spraying them with milt (fish s p e r m)

  • fish angels: why did my male angel not want to fertilized the eggs but did last time? Just two weeks ago and our bushy nosed sucker fish ended up eating them.
  • Riffy: Informative! Thank You
  • Caribbean girl: Hi John
    Can two female angels pair off?
    I have six angels in my tank, two of them tend to habour one corner of the tank and run off all the other angels. I noticed that the more rounded one, I assumed to be the female, tubes were beginning to show, I removed them and placed them in their separate tank and soon after, eggs were laid. Unfortunately they began eating the eggs so I removed the parents. Many of the eggs have started getting while. I am just wondering if they would happen to be two females.
  • johnarthur: Two female angelfish have been known to spawn but the eggs are always infertile and quickly grow an opaque, white fungus. First time spawning pairs often eat their eggs. A spawning pair must have its own aquarium of generous size.
  • Caribbean girl: Thanks John, I really hope that my pair which seems to stick together all the time are not two females.
  • Jam: It’s called sexual dimorphism not anthropomorphism. Anthropomorphism is giving human emotions to animals or objects.
  • thea: @Jam. Just goes to show you that JA was right when he said “A bunch of Latin words that I do not know.” 😉 But you are right. It is sexual dimorphism. JA knew that, he used both words correctly many times, it must have a been a slip of the keyboard. Unfortunately he is not that active on MAC anymore. We do miss him, he was a very vital part of MAC when it was just starting out. I will correct the mistake.
  • L.C.Coutinho. Ph D. Amature aquarium lover.: I found your description most interesting 🤔 I liked it....

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