I kinda talked about this on my "pleco-powered" thread, but then I thought I'd post it over here, since there's probably a better chance of getting it answered.
I've brought in some of my tilapia for the winter, just in case I can't keep the greenhouse tank warm enough to keep them all alive out there. I've been trolling the Intarwebs all day trying to educate myself on how to tell which ones are males and which are females (besides trying to hold them and count holes, which I suspect would probably end badly, without telling me anything, since as a nurse, I've had some experience with how real life things tend not to look nearly as simple as they seem in illustrations and diagrams).
I know they're sexually dimorphic, but none of the descriptions I found went quite far enough to tell me for sure what I've got...they'd describe, for instance, what a male looks like, but then they wouldn't clearly say which of those things doesn't apply to females...so I'm still confused.
I know for sure this guy's a male, so that's something:
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File comment: Male Mozambique
2013-11-01 19.48.27.jpg [ 198.01 KiB | Viewed 4872 times ]
2013-11-01 19.48.27.jpg [ 198.01 KiB | Viewed 4872 times ]
I know because he spent the whole day today building himself a nest.
Also, because of his coloring, and his dorsal and anal fins that extend past the base of the caudal fin, and because his face has a dip in it and his lips turn upward. What I'm not entirely sure of is these guys:
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File comment: Mozambique Tilapia
2013-11-01 19.56.08.jpg [ 225.6 KiB | Viewed 4872 times ]
2013-11-01 19.56.08.jpg [ 225.6 KiB | Viewed 4872 times ]
The one in the middle, I figure, is either female or juvenile. Or both. S/he's about 3-4" long. The two on either side of her, I *think*, are males, for most of the same reasons I listed above. (They're both about the same size as the black one.) But I keep talking myself out of believing myself, partly because I don't think their fins are quite as long as the black guy's are, and partly just because he's not as aggressive toward them as I think he'd be...when they poke around his nest, I can't really tell whether he's flirting or telling them to scram.
I've also spent a lot of time staring at the rest of the ones I've brought inside, which range from the size of the (?) female in the second photo down to about 2" long. They're all the same color as her, with dorsal and anal fins that reach just to the base of the caudal. Some of them, like her, have a blush of red on the tips of their fins and tails; others don't. I don't know whether that's a gender-specific thing or not.
Can anybody clarify any of this for me?
