4 replies to this topic

[mattknepley]

I've made an observation that has me curious. As you may have seen, yesterday I acquired a pair of Notropis hudsonius on a quick trip to a local river. After extended observation and acclimatizing them to in-home temperature, I was preparing them for transfer to their new home. As I was holding the photo/observation/acclimatization tank up to check them one last time, one made a most impressive verticalization between my fingers, out the top, into the air, and plummeted about 4.5' to the floor. It was out cold and never recovered. Kanus mentioned he finds these fish flighty and hard to net, which my observations in the river and at home back up.

Upon adding the surviving spottail to its new home I saw a near immediate change in the behavior of my Notropis chlorocephalus. I have a school of 11 of them in the 55 gallon the spottail went into. When I first put them in the 55, the greenheads went into a tight school, facing into the current provided by one of those in-tank water fans. (Or whatever they are properly called...) But after about 14 seconds they recognized me as the food dude, loosened ranks, and jetted to the surface anytime I went near the tank.

When the spottail went in, the greenheads went into a tight school very quickly. That was yesterday afternoon and as of 5am today they are still in one. They do not rise to the surface when I am near the tank, and left food on the surface last night when they were fed. I have heard people mention the fear aroma that fish give off upon capture and that they are glad when they can get new captures out of the water they have been held/transported in as the concentrated "fear stink" is stressful. Could spottails be particularly "stinky fish?" The greenheads allow it to swim with them, so they aren't afraid of the fish in and of itself. Being a Notropis, the spottail had settled in enough to eat frozen brineshrimp drifting in the water column with the greenies. But could it be emitting enough aroma to keep the greenies nervous? No other fish behavior changed, that I can tell. Will be doing a water change later today; wonder if that will have any effect on their schooling.

[Michael Wolfe]

Fish In Focus has your answer...

http://www.nanfa.org...utipinnis.shtml

"Schreckstoff"

I think that Chris Scharpf wrote a nice AC article on this some years ago also.

[mattknepley]

Thanks, Michael. I had forgotten that f.i.f.; had read it a while ago. I remember you saying something to that effect before too. My surprise is the strength of the effect. I'm on a quick work break here at 9:14, and the N. lutipinnis are just beginning to loosen ranks now. I noticed also my Cyprinella chloristias were much more aggressive than normal this AM and two of them were hanging with the greenheads. (I forgot to mention that earlier.) They never hang with the N. chlorocephalus, and their behavior didn't change when the greenheads were added. I'm guessing the spottails must just have B.O. that hangs longer and stronger than 11 greenheads! Especially considering the spottail had calmed down enough to eat supper last night.

[mattknepley]

Very interesting observation! Perhaps those hudsonius have a particularly strong schreckstoff and/or exude it more than other fish. That could have something to do with their frequently nervous/flighty behavior.

I'm kind of wondering if that isn't the case myself. Seeing as how these guys are schooling fish I will be trying to wrangle some more hudsonius so it's more comfortable. If the situation repeats we might be on to something.