Swordies have their disappointing moments too. Even though I like them for their tendency to vary their colors with each generation and it's not just the tail, like guppies get, it's the whole fish and it's bigger.
The problems with swordtails:
- aggressiveness, even between females. If there's no second male, then it's the females arguing over stupid stuff. If there's only one female, she will either be harassed by the male, or the male will have his tail handed to him (my swordies' case). The good side is that they're not as aggressive as bettas or other mean fish.
- You get so many of them that you just got to have a population control.
- Each generation can have some that are rather plain looking / have no color at all on them. However, I spared a half-white half-black fry (which also has a tiger stripe on the middle of his body). But I don't usually like transparent fish.
- Tons of poop strings. Although they do clean up after themselves and it's basically the only food my plants get anyway...
- Skimming the surface for food. Before I did some research on this, I thought they didn't have enough air or something and kept changing water 90% (since I didn't have a nitrite tester back then), now I see why they do this: when there's food there, they suck it off the surface.
- Some of their fry are EXTREMELY STUPID! They are so tiny and yet dare to swim out in the open... and get eaten first thing. WHY must they leave cover like that? There's enough food falling in there, my hoplo's usually on guard around there... yet they just wander away and get eaten by the female swordies...
And then there's this big fry I call Ninja... He gets bullied by a week-old fry that's half his size! That thing could pass for a flea next to him, but it chases Ninja all over the tank if they meet. *face-palm*