Guppies are smarter than I thought

Thursday, 30/09/2010 ≅17:29 ©brainycat

I've been "breeding" guppies for about five years now. I'm not a serious breeder, I'm doing it trailer-park style whereby I remove males that don't have traits I like and let the population adjust accordingly. I'm selecting for rainbow-shimmery bodies, and for a while the population was coming up with a lot of very beautiful fish. Unfortunately, I've been away from them for about 8 months and they weren't very well cared for. There's about a month's worth of 80% water changes ahead before they'll be healthy again. The fish born during this time are showing all kinds of odd congenital issues; most of the males have a "sword" at the bottom of their otherwise feminine-looking tales, and are very dull in coloration, with brown bodies and a few spots. Also, the plecostomus that was about 12cm long is suddenly 25cm long and has probably 3 times the mass it did last time I saw him. With all the nitrites and nitrates in the water, it's no surprise it's been able to eat well.

Also, they behave differently. I haven't had a lot of time to really gain any empirical data, but my impression is that these "feminized" males aren't dancing with the females as much as darting at them. I thought it was because the water was so bad, they either weren't able to breed or they were being aggressive as a result of being uncomfortable. Interestingly, ascientificnature just wrote up a post about a study that shows that male guppies are able to adjust their mating strategy based on their phenotype. Large, colorful males court females by dancing with them, while drab males actually rape the females by darting at them and copulating before the female can swim away. I had no idea guppies did this; I always thought the darting behavior was some kind of aggression (not that rape is act of love, but we're talking about fish, not primates) because the females always swam across the tank afterwords.

Once I've got the tank healthy again, I want to order some show guppies. Now, I'm not a big fan of breeding any species for shows - I think the criteria are entirely too subjective for anyone to empirically say a particular specimen is better than another specimen. As I've said before, it's populations and the way genes recombinate and express themselves across herds and schools that interests me. That said, there are some amazingly beautiful strains available for sale (at a price to match) and these will be the first "foreign" genetics introduced into the system for at least 3 years, maybe longer.

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