Skirt tetra questions

Hello! I have 4 skirt tetras (3 black and 1 white) that I brought home from an office tank. I would like to know a little more about them but as usual, I am finding conflicting advice online. Things I would like to know:

1. How do I tell if they are male or female?
2. I read that the "long-finned" variety (which is what these are) are really just males. Is this true?
3. How long do they live? I've seen everything from 3-7 years. Anyone with personal experience? How long have yours lived?
4. Are the black variety more hardy than the white variety? The office started out with 4 of each. After 4 years, 3 of the black remain but only one of the white. Is that typical?

At the office, the fish were being fed from an auto-feeder, so became extremely people-shy. There were lots of places to hide in the tank and they did every time someone came to look at them. So, I brought them home to make room for a better display fish at the office. So, now these guys are at my house and I do not use an auto-feeder and they are learning that people = food. The largest of the group is the boldest. He/she struts around the tank like the Boss! No fear! Comes up to the feeding corner like all the other fish when I walk up to the tank. (I have about a dozen other small tetras and espe rasboras in the tank.) The other 3 skirt tetras are still very shy though. When I brought them home, the other 2 black skirts faded almost to complete silver from extreme stress. I felt horrible. Their color is back, but they are still very shy. I often work from home and can see them when they don't notice me because I've been still for long enough, and they do come out. They don't roam the entire tank like the largest one does, but they do venture away from their favorite hiding corner. This was also their behavior in the tank at the office though, so maybe they are just back to what is their normal?

All of which leads me to my next question:
5. If I got more of them, would that stress them out or make them feel better? I'm afraid that because these are already 4 years old, that new ones would disrupt their social hierarchy or little group dynamics or whatever it is they have. They are used to each other. Should I mess with that? The elderly don't always like to hang out with young whipper-snappers. Will it stress them? Or will it, conversely, reinvigorate them and make the timid ones feel braver? Thoughts? Direct experience with this situation would be extremely appreciated. Especially from anyone who has kept this species long-term.

6. Is there anything else I should consider or know about or would find interesting?

Thanks so much!

p.s. i have soft water, 0 ammonia/nitrates/nitrites, weekly water changes of 50% - 70% depending on the week. The tank is planted and several years old.

Ok, here we go..

1( The females are typically plumper/bigger than males. Also the males front edge of his anal fin slants back towards his tail.

2( Not true, both females and males can have long "skirts". (Aka fins)

3( Just from my research/friends having them, they will anywhere from 5-7 years. But that is only if they are well kept and have good water quality.

4( No, the black and white are the same fish, just different colors. It just depends on the breeder. the other fish probably died because of poor water quality. What are your parameters?

BeckyCats said:

He/she struts around the tank like the Boss! No fear! Comes up to the feeding corner like all the other fish when I walk up to the tank

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Most likely a female, because you said it was the biggest one. you can tell by the way I described how to sex them above.

BeckyCats said:

5. If I got more of them, would that stress them out or make them feel better? I'm afraid that because these are already 4 years old, that new ones would disrupt their social hierarchy or little group dynamics or whatever it is they have. They are used to each other. Should I mess with that? The elderly don't always like to hang out with young whipper-snappers. Will it stress them? Or will it, conversely, reinvigorate them and make the timid ones feel braver? Thoughts? Direct experience with this situation would be extremely appreciated. Especially from anyone who has kept this species long-term.

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I think if you got more, there would be less stress. The female is trying to be territorial. They can be very mean to other fish. If getting more doesn't work, you may have to get rid of the mean one. My old ZD was very aggressive to my neon tetras. I had to move him to a tank by himself because he was so mean. Fish can be very mean at times.

BeckyCats said:

6. Is there anything else I should consider or know about or would find interesting?

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What other tank mates do you have? Do you have a lot of hiding places? If the tank is bare, then the fish will be more stressed, due to the fact that they have no hiding places.

Thank you for taking the time to answer. I appreciate it!

So, to answer your questions:
Water parameters are stated in original post. As stated previously, the others died before I brought these home to my tank. My question was not why they died but whether, in people's personal experiences, the black skirts tend to be hardier than the white ones. Three quarters of the white ones died in their previous home, whereas only one quarter of the black ones did. I'm wondering if was just coincidence or is it an actual thing? All-white animals are often weaker in some way and I'm wondering if that is the case here too. It's just a curiosity thing. Now that these guys have acclimated to their new home (been here about 2 weeks), I'm fairly sure they are over the initial trauma and should survive their expected lifespan.

With only four to compare between, it is difficult to determine whether any look different from each other. They all seem to me to have similar fin shapes etc. They may all be male or all be female, which would make it impossible for me to "compare" them to each other to determine a difference in the sexes if they are all the same sex. I read from the internet both that females are larger and also that males are larger. Do you base your information from internet sources? If so, which sources?

With my other tetra species, the females are easier to spot as being rounder and slightly larger, but again, only in a mixed male/female grouping. Skirt tetras have a different shape (being flatter, more like an angelfish, than a typical torpedo-shaped tetra), so are trickier for me to see the differences (again, if there are even any differences, since these may all be the same gender). I will post pictures.

There are lots of places to hide. It is a planted tank and has rocks and decor as well. If they choose, they can literally swim from one end of tank to the other almost without being seen.

If you post pictures of the 4 you have, I should be able to tell what gender they are.

Here are some photos of the fish. I'm sure I dont need to explain the difficulty of getting a clear shot. Ha ha!

Hmm.. very hard to tell from the picture. Which ones are bigger/more plum than the other? As I said before, very hard to tell from the photo.

PheonixKingZ said:

Hmm.. very hard to tell from the picture. Which ones are bigger/more plum than the other? As I said before, very hard to tell from the photo.

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None are more plump the others. One is larger than the others, but they all have the same shape. I think they are either all male or all female. But as I mentioned, online sources differ as to which are males and which are females. I was hoping someone with experience would be able to say which are which based on observed behavior, particularly when mating, which would be the best indicator of gender.

As these fish have been together for four years, they are nearing the end of their expected life, which is 4-5 years. Of course, many of our fish if well cared for can go well beyond the normal life expectancy, but given that this species has been commercially raised for decades that means it has been genetically weakened as a species and not likely to be as healthy or long-lived as wild fish.

Second point from this is that this is a shoaling species and normally a group of more than six would be advisable to avoid fin nipping within the species. But given the age, it is ofteen better to simply let the last of the group live as comfortably as possible. Adding juvenile fish (which store fish would be) to a group of 4-year olds could be disastrous, especially with a species like this one that does normally have some aggressive tendencies.

As for gender, males are slimmer than females (best when viewed from overhead) and have something of a point to their anal and dorsal fins compared to the female's. Given that this fish tends to fin nip among itself, and the photos do show signs of this, I won't guess. But the "white" fish is not this species, it looks more like an albino form of one of the "Rosy tetra" species.

The females tend to be a little larger than the males, this is true of most tetras. Also as they age their color pales but that can also be caused by stress.

I agree with the above. Everyone pretty much just recapped what I said, Females are larger/more plump than males.

Byron said:

As these fish have been together for four years, they are nearing the end of their expected life, which is 4-5 years. Of course, many of our fish if well cared for can go well beyond the normal life expectancy, but given that this species has been commercially raised for decades that means it has been genetically weakened as a species and not likely to be as healthy or long-lived as wild fish.

Second point from this is that this is a shoaling species and normally a group of more than six would be advisable to avoid fin nipping within the species. But given the age, it is ofteen better to simply let the last of the group live as comfortably as possible. Adding juvenile fish (which store fish would be) to a group of 4-year olds could be disastrous, especially with a species like this one that does normally have some aggressive tendencies.

As for gender, males are slimmer than females (best when viewed from overhead) and have something of a point to their anal and dorsal fins compared to the female's. Given that this fish tends to fin nip among itself, and the photos do show signs of this, I won't guess. But the "white" fish is not this species, it looks more like an albino form of one of the "Rosy tetra" species.

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That's what I thought regarding adding more. I was afraid of the age difference and the fact that this group is used to each other. I will let them live out their days as they are. So, your experience is that they live 4-5 years, not 7?
I think the white fish has the same shape as the others but the photo is not great. You may need to pull it up to see it. The fins are actually mostly clear, so very difficult to see, but they are the same long, flowing shape. Also, the body shape is the same.

I had looked at this fish for my tetra tank and I think 4-5 years was right. That is good that you will let them live out their lives and not add younger fish since they are so old already.

Sounds like if all of the fish are male or all female, then it is difficult to determine which they are. I will just have to wonder, I suppose.

At their age they may not be interested in breeding

Retired Viking said:

At their age they may not be interested in breeding

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LOL! I imagine not. I was really just curious. Like when you ask if a baby is a boy or girl. Doesn't really matter, one just wonders. I suppose I should try to be less binary.