Is behavior a reliable indicator to determine if a fish is male or female?

[MarlonnekeW]

Hi everyone,

I'm still pretty new at keeping Loricariidae and one of the hardest things in my opinion is determining if a fish is a male or a female. Especially with species where the physical differences between males and females are difficult to spot. Two of my fish (Ancistrus claro) are cleary females and I also have a definite male Panaqolus maccus. When observing these fish, I've noticed differences in the behavior of the females and the male. Especially in their use of the caves. The females hardly even go inside and prefer laying on top of a cave, while my male. P. maccus spends a big part of the day laying in the entrance fanning.

About three months ago I bought a juvenile L201 and I have no idea of it's sex. A few days ago, it started to visit one of the caves more often and at the moment it's spending a lot of time inside the cave. So if I look at the behavior of my other fish, this would suggest that it's a male.

So I was wondering, is behavior a reliable indicator of the sex of a certain fish, or can this only be determined by physical characteristics?

[pleconut]

Hi MarlonnekeW, I don't go on behaviours alone but I have used it as an indication, as part of the whole picture when it comes to determination of sex of my plecos. I will give you an example, at around 7-8 cms my L397s were all wanting caves, therefore I thought (wrongly!) i had mostly boys, and then done all i could to try to get females. Now I have 3 definite adult females - happy to hidout in caves and wood. 2 definitely adult males - always in caves. Then 3 youngsters at 7-8 cms they're not as territorial around caves. I've also really improved in my management of them and they have more hiding spots now, so hiding more in the wood. So I'd say females. Also I had an extremely cave defensive one that's turned out a female, but now she's only cave defensive if her favourite male is in the cave, if he's not she's then defensive of that entire region of the tank. With no consistant or clear or conclusive behavioral indications historically in my group. I wouldn't go on this alone but do use it partly to help determine sex. Panoquolus is my only area of experience, so I'm not sure how it is for other genera.
Edit. With all my adult males, Ancistrus and 2 Panoquolus sp fan all day long even if theres no eggs the female's don't when in the caves.

[MarlonnekeW]

Hi Teresa,

That's very interesting, thanks! I've only had experience with 2 female Ancistrus claro and one L144 female and I don't think I've ever seen them in any of the caves. Last Saturday I got 3 more juvenile claro's and I hope at least one of them is a male, so I'll wait and see how they will act as far as the caves go.

[pleconut]

With my ABNS that spawned for the first time a few weeks ago the males I had 2 (LFS sold me the wrong sex when I wanted a trio 1 M 2 F) the males showed no interest in caves or the female at all until the day of the spawning. But at least with bristles you get an idea of the sex sooner.
Good luck with them.

[smitty]

Though I think Behaviors can be an indicator. So can tank mates and conditions in the tank. I have had some very aggressive females and males. But with the females because of how they behaved I initially thought they were males even though the body shape made me think otherwise.

[MarlonnekeW]

Thanks, that's very interesting. So if there's aggression between two fish, this doesn't automatically mean that they are both males? Was the aggression of the females directed to other females or also to males?

[Jobro]

I really don't think that aggression should be used as an indicator. Caving or not caving can be more of an indicator. But still not even close to bulletproof.
I bought a P. Maccus. I was damn sure he was a male, going by odontodes and body shape and vents. Still "he" is always outside of caves while other P.maccus are caving. I still don't know it's real gender for sure.

With your L201, yeah on hypans, it's very likely males will be caving a lot more than females. But that usually only goes for grown ups. juvenviles seem to be just doing whatever they feel comfortable with. A female will not cave if she knows there are bigger males around, that might trap her. But she might cave when she is alone. I noticed that on my BNs when I split them by genders and on L260s. However, telling grown up healthy hypancistrus genders apart should be quite easy. I always had trouble telling them apart, the reason was I only ever did see young males Once you put a mature male and female next to each other you will be able to tell them apart easily.

[MarlonnekeW]

I guess I'll just have to wait and see and be very happy with my claro's, that will be very easy to sex in a while ;).

I do get your frustration with the P.maccus. When I bought my newest edition I was quite sure it was a female. But after I took a picture of it from above and looked at it on the computer, I really started doubting myself. It gets along pretty well with my other P.maccus, but after a week, it got really aggressive towards my Corydoras schwartzi, which is not very 'lady like' ;).
Even with the other one, I'm not sure. It has very obvious odontodes and spends a lot of time in the entrance of a cave fanning, but recently it was 'hanging' on a piece of wood so I could take a good look at it's body shape and I've noticed that it's very wide between the pectoral and pelvic fins. So based on body shape I would say that it's a female, but that makes no sense in combination with the odontodes and the fanning.

[Jobro]

If you feed P. Maccus with anything but wood alone, they will get "that" body shape you are talking about. It's more about the head than the belly with well fed P.Maccus I guess. Did you check out Eric's (bekateen) thread about his P. Maccus?

BN like your claros are supposed to be sexable by touching their nose/snout. Hard snout = female. soft, jellylike snout = male. But I never tried that. Also not sure if it's only for the common BN or every kind of BN, but I guess it would have to be for all of them.

[MarlonnekeW]

Ok, thanks. Then I guess he's definitely a male ;) To be honest, I would be fine either way, as long as the get along. I'm not really trying to breed them. If the do it's fine, but if not that's ok as well.
At the moment, because of the problems with the schwartzi's, the new arrival is in an aquarium with only dwarfcory's. Since then, I haven't see any aggression whatsoever. I want to put them back together in a new 70x40x35cm aquarium soon, but at the moment I'm really doubtful about the other fish. I could house them with my Corydoras habrosus (and maybe add 1 or 2 more), which I really like to breed, but I'm not sure if the P.maccus will leave the cory eggs and fry alone (with the habrosus it's hard to remove the eggs, because they spawn between the leaves of plants and it's hard to find the eggs). In that regard a slightly bigger cory species (around 5cm TL) would be better, because I would have to remove they eggs anyway, to protect them from the parents, but this might lead to the same aggression problems as with the schwartzi's.
So hopefully I can reunite them soon in their new aquarium and I'll be able to tell the sex of the second P.maccus.

[TwoTankAmin]

I can only speak to those species I have kept and spawned. These include a variety of tank strain bn, P. compta, H. zebra, L236, H. contradens, L450. L236 and L173b. based on these fish i can report that the only way to confirm the sexes of these fish 100% id when they get to the age where it is easy to cent them. You can see their tubes when they are out. However, I find behavior to be the second most reliable method once they reach spawning age. I usually find it better than looking at odontile hairs (except for the P. compta where males get covered in this over the rear 1/3 or their body), head shape or pectoral shapes. These characteristics can give strong clues but are not as reliable as behavior for me.

The key, as mentioned is they need to be close to being ready to spawn. One thing many folks may not account for is the fact that in a spawning group both the males and the females have a pecking order. Only the top females get to spawn, not the subbordinent ones. By this stage it becomes clear that females use caves but do not claim them. However, in a decent size group, the top males get the best sites because they have won the fight over them. So not all the males in a tank may claim a cave.

However, the fewer fish in the tank, the easier it is to use behavior to sex. A perfect example is a purchase I made a number of years back for my zebra breeding tank. I had lost a couple of the original fish and spawning has stopped for some time. My thinking at that time was that the fish I had lost were males and that I needed to boost the number of them. So I arranged to purchase two new wc adult males. These fish went into a very nice small tank set up to Q them for a couple of months.

Almost as soon as they two "guys: hit the water, one claimed a cave and the other did not. The tank has wood, rocks and 3 caves from which the two fish could choose. But day after day I would see one fish in the same cave and the other one almost never in one. The second would park in a cave now and then but was mostly spotted hiding in the wood or rocks. Back then I had never tried to vent them, I managed to take pics of both fish, including from below, and posted them here and on another site. Word came back to me from a well known Hypan breeder that the fish was definitely a fm. I knew this would prove to be the case because the behavior of the fish made this clear while its shapes and odonitile growth did not. But i needed confirmation.

I have notice a few other traits in the fish I have kept in terms of the offspring and the changes in behavior they show as they grow, Newly released fry congregate. I can find almost all of them huddled together in a couple of tight fitting space in the tank. As they age they begin to break into smaller groups. It is more work to locate fewer of them. As they get even older a few will break away from the group and start to hang out in their own spot which eventually is a cave. As they hit the point when there is a pecking order established, the number of claimed caves will drop but the more senior males will pretty much use the same caves. There may be an occasional swap between two of them if the opportunity arises, but the net result tends to be the "best" caves are always claimed and never by females.

Since, I have not kept enough varied species to generalize, I will leave that to those who have first hand knowledge. But I am thinking that many of the smaller species of plecos may not be all that different in this respect. Bear in mind that in nature the aquascape is not man made, In our tanks we provide whatever layout the fish must use. So my point of reference are how they behave in tanks and this is likely to differ somewhat from what goes on in the wild. A fish shunned in one spot may be able to move 100s of yards up or down stream. This is a lot different than what a 3 to 6 or 8 foot tank (.9 to 1.8 or 2.4 m) permits. And I am a believer that environment influences behavior especially in the confines of the aquariums most of us use in our homes.

As always this is just one man's experience and opinion. And I should state I am really bad at sexing most plecos without venting them or at least observing them for a while as adults.

[pleconut]

That info has helped me also, the female I mentioned that chases of the all the others could either be a dominant female or a subdominant male. If its the latter then I suppose that separating it for a time would put it on par with the two males by bringing out more of the male characteristics?

[MarlonnekeW]

That's really interesting information, thank you!
I'm already looking forward to seeing the group dynamic with my claro's.

[Linus_Cello]

I
The key, as mentioned is they need to be close to being ready to spawn. One thing many folks may not account for is the fact that in a spawning group both the males and the females have a pecking order. Only the top females get to spawn, not the subbordinent ones. By this stage it becomes clear that females use caves but do not claim them. However, in a decent size group, the top males get the best sites because they have won the fight over them. So not all the males in a tank may claim a cave.

...

A fish shunned in one spot may be able to move 100s of yards up or down stream. This is a lot different than what a 3 to 6 or 8 foot tank (.9 to 1.8 or 2.4 m) permits. And I am a believer that environment influences behavior especially in the confines of the aquariums most of us use in our homes.

So even in a 6-8 foot tank, only the alpha female gets to spawn? Or can there be multiple spawning females in larger tanks?

[pleconut]

I have 2 adult L397 males taking up caves at either end of a 4 ft tank both get tgeir share of female attention, I dont think there's competition between them, but the group hasnt starting spawning. I dont know if this will change when they do.