Evolution in a microcosm

["Anthony Baker" <anthony_w_baker@hotmail.com>]

So, last night I witnessed Evolution at work in my 29G plant tank.  The tank 
contains a trio of Blue Rams, a couple black neons, 3 molly fry, 3 ottos, 2 
SAEs and ~12 ghost shrimp, bunch of red ramshorn snails and MTS.  Because 
this is a aquascaped tank, I didn't have any "normal" spawning locations, 
just a few artistically placed rocks and driftwood.

The tank stats are:
KH / GH: 3-4/6
CO2: 25-35ppm
pH: 6.65-6.70
NO3 - ~5-10 (added weekly for plants)
PO4 - ~0.5
Weekly water changes.
Temp ~81F

Anyhow, after I fed the fish their allotment of live blackworms, I moved on 
to feed my other tanks.  I returned 15 minutes later, and sure enough, the 
male and the "alpha" female were dancing around a little depression in the 
substrate (flourite) hidden behind some tall plants.  I peered in and could 
see ~75-100 eggs (not bad for a tiny female) right on the flourite.  The 
male was busy fanning the eggs.  The interesting part: the "beta" female, 
who lately has been chased by both the a-female and the male, kept coming up 
to the pit and appeared to "entice" the male away from the eggs.  Then, she 
would circle around the whole tank while being pursued by either the male or 
both the male and a-female.  A few times, the b-female would circle back to 
the pit and quickly gobble down a few eggs!  The male would chase her away 
again, and the whole thing would start again! The male also began chasing 
the a-female around, allowing the beta-female even more snack time!

Evolution at work!  The b-female was clearly eating the eggs to increase her 
fitness level and simultaneously reducing the chance of the a-female 
spreading her genes!  Very interesting!  Another consideration is that it is 
quite likely that the trio are genetically related -- probably even siblings 
-- as I got them from the LFS.  In many higher animals, genetically related 
conspecifics often take _some_ responsibility for care of young -- eg. 
"aunt" chimps often take turns caring for baby chimps or watching juveniles 
while the mother gets some relaxation.  Apparently not so with Rams!

I also think I was pretty lucky to get two true females and one male -- I 
was a bit worried after reading about the lack of females being imported 
from the Far East.  Perhaps the trio was even from a local breeder.

Well, an hour later, I checked back on the tank and noticed that the male 
and alpha-female were doing a "spawning dance" on the other side of the tank 
near the driftwood.  The female's ovipositor was still very extended and 
both had full coloration. The beta-female was no where in sight, and it 
looked like most of the eggs were gone.  So, I am hoping they do better on 
the next round!

I am not prepared space-wise to dedicate a tank to breed these fish, but 
wouldn't mind having a successful spawn in their present tank.  If anyone 
has suggestions that might help, I would appreciate it.  I could pull out 
the other female, but think that she might be next in line to lay eggs!  I 
added a small clay tray (for flower pots) with some fine sand in it, so 
maybe the Rams will like that more?

TIA,
Tony
BTW - My new pair of A. trifasciata is settling in nicely and my new male 
double-red aggie is adjusting to his new home... Still seems a bit ragged, 
but hopefully some good food will fix him up soon!



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