[Hanalei]

I'm trying to interpret the behavior of the two sunset swords:

the male spent some time obsessively swimming into the stream of where the filter water pours into the tank (rear hanging AquaClear mini filter). Basically, swimming in place against the flow. The female would swim over and the male would lunge for her, causing her to dart away to the opposite end of the tank. Then she would come back. Sometimes she would dart away of her own accord. This went on for sometime. The tuxedo female was doing her own thing during this.

A little while later, down in the rear by the heater, the male and female sunset looked like they were trying to "get into position," although I'd have to say it was the female who was the more active and the male was more passive.

This morning the male and female sunset were sleeping side by side under some foliage. I don't know, but it seemed unusual.

And now it seems like the male is spending more and more time obsessively swimming in place against the flow of the filter.

Is the tank too small for him and he's fulfilling a need to swim hard?
Is there something about the water that doesn't agree with him? (The females seem fine and all the readings seem normal.)
Is this a variation on some sort of mating behavior?

Interested to hear any thoughts on this.

 

[mousey]

I would be treating them for gill flukes myself. Sometimes fish with flukes will swim in the water flow to try and get more oxygen. I had a couple of rainbow fish do that. Then they started to sit on the bottom of the tank and then they were dead.
However I have had fish that just seem to like to play in the current for short periods of time.
It is really hard to decide on some things but generally i have found that parasite treaments do not do any harm to the fish , plants or biofilter.
Some people I have read on other forums treat for parasites every 3 months or so as a prophylactic.

 

[AvocadoPuffDude]

Swimming against the flow is just because he likes to swim in a strong current. It doesn't mean much, other than it seems like fairly healthy behavior.
Mating behavior in swords is similar to most livebearers; when the female is giving birth and right after, the male can detect it (by smell I suspect) and will chase her down like nobody's business, he'll be obsessive about trying to mate with her. A lot of displaying, darting in front of the female, and flaring his fins, doing a little back and forth dance with a curved body usually, then BLAM - darting over and trying to mate, and the more she swims away the more fervent his attempts will get. It can go on for more than a day, this is why you want more females to males, so the attention is spread amongst all the females. Otherwise, a male can actually pester a female to death, especially while she's birthing. She needs some resting time in there, some hidey places to get away from the male's attentions.
Sleeping under a leaf together at night, although a romantic notion, means nothing other than it's a good place to sleep at night for them and they both found it. Fish will find a place of low current sometimes and rest, that's just normal behavior.
All of the other behaviors you mentioned are just random sword behavior, nothing at all to do with mating. I've NEVER seen a female approach a male and try to initiate mating, getting in position or anything at all like that. They really don't have to do that with a healthy male around, trust me.
Keep one male to 2-3 females minimum for best results.
I disagree with the concept of preventative medicating your tank. I haven't medicated my tank in over 10 years, and don't quarantine my fish, and I rarely lose a fish to disease or infection. Fish kept in good conditions - not overfed, water changes, filter changes, correct pH and chemistry - are usually healthy enough to fend off infections. I've never witnessed a fish swimming against the flow of water do so because of infectious disease - flukes or otherwise - ever. Sick fish can take on some odd behaviors, but swimming against the stream isn't usually enough just in and of itself, to signal anything wrong. If they're SHIMMYING and going against the stream, MAYBe.
Good luck to you!

 

[Hanalei]

Thanks mousey and Avocado Puff Dude. As you may know from my most recent Fin Rot Diary post, the male swordtail died yesterday, not sure of what, as he was eating vigorously the previous night and the two females are still okay as of this morning.

I don't know how I would go about ascertaining if it was gill flukes. And he may have been "shimmying", but at my beginner stage, I don't think I would recognize shimmying the first time I saw it.

 

[mousey]

well as you can see there are different opinions about things so fishkeeping is not always easy.
The best thing is to be able to start out with healthy fish and learn what you can about normal behaviour for your fishes. I liken it to being a mother of children- you will know when your kids are sick if you know how they act when they are healthy.
Some people recommend quarantine for every new fish and prophylactic treatments and some don't- you have to chose for yourself what path to take.
However as one other member here would tell you, if you keep real expensive fish and you add a new fish to the mix that carries something into your tank and it wipes out your tank you are going to want to quarantine.
If you have a really good source for buying fish, like a local breeder, you may not need to quarantine.

 

[AvocadoPuffDude]

I accidentally posted this and don't know how to delete this response.