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In June 2010 I was fortunate enough to get 2 pairs of this quite distinctive fish. When I first glanced at these busy fish in their tank, my first thought was that they were Phalloceros caudimaculatus. This was the first time I had ever seen X. milleri and the few photos I managed to find later, showed a much plainer fish. They are endemic to Lake Catemaco in Mexico and often referred to as the Catemaco Platy. I wasn't sure what size they would get to, but the females were around 3 cms and the males were around 2.5 cms, although the females being much plumper the size difference seemed greater. Both sexes had a slight gold and silver sheen behind the black speckles but the density of speckles varied considerably;- some of the females were far more speckled (quite the reverse of my Phalloceros caudimaculatus).  Although the speckles on the males were often less dense than on the females, the one really striking feature of the males is a conspicuous black gonopodium.  The males pursue the females almost incessantly rather like the Black Chinned Livebearer (Girardinus metallicus). Even when the females are feeding, the males try to take advantage of their distraction. With such constant intent, the females are soon gravid! Fry It wasn't many days after that I was caught out with a surprise first drop of fry. I was trying to get a good photo of a male when I saw a small fish swim past my lens! As with all Livebearers, the question was whether to leave the fry with the adults? I decided to play safe with this first brood and remove them;- I didn't know if any had been eaten and therefore I couldn't tell if my meagre 6 fry was the total drop. Literature check on milleri broods... With reference to the expected drop, it's interesting to note the differences between three sources of Literature;- 1 In "Platies and Swordtails" by the late Derek Lambert and Pat Lambert it states;- "Broods are born on a monthly cycle with numbers up to 50 being known, but about 20 being average." 2 In "Livebearing Fishes", John Dawes states;- "Between 30 and 40 fry every 5-6 weeks." 3 In Baensch Vol 2, it states;- "Between 3 and 8 fry with a maximum of 10". For the moment my total seemed to confirm the latter's estimate? Future drops would be interesting and if consistent, would support Baensch ...... However for this species there are different morphs, colour variants and sizes which means there will inevitably be some extremes of drop sizes. I briefly grew them on in half a toffee jar with regular water changes and when they were 2 weeks old, I put them in a 24" tank with a divider. My dividers do have their limitations with small fry;- almost immediately afterwards, I found out by accident that that the young fry had indeed reached a sufficient size to be safe with the adults;- two youngsters had squeezed past the side of the divider into the adult half! At this stage the fry were around 5 mms in size and a plain, pale beige colour. By the time they were 3 weeks old, the fry were around 7 mms in size, and significantly just beginning to show the dark speckles on the rear half of the body.  The spots on the juveniles varied quite a lot, but by the time the fry had reached 1.5 cms, the males were beginning to look a little more like the adults but lacked the intensity of speckles seen on the adult females and didn't as yet have the black on the gonopodium.  Subsequent drops certainly supported Baensch's information as my highest drop was only five, which meant that for a Livebearer, building up good numbers was a slow job! I also had to re-consider my "fry are safe with the adults" conclusion! I think that when the youngsters got past the divider, they had grown on sufficiently to be not considered a snack. In later drops which were still small, I felt that one or two newborn fry were lost due to the adults' predation, often leaving perhaps two or three fry which managed to avoid their attentions. However, I have to say that I never actually saw a fry being eaten. A problem evolving... I also found, that due to losing some fry as well as some juvenile males (no visible reason!) and numbers building up very slowly, I had an unwanted skewed ratio;- eight months later, females were taking up 90% of the total. Apart from my source, I knew of no other aquarists to do any "swaps" with, so unless subsequent drops yielded more males, I would have a problem moving any fish on. It would be interesting to know if other aquarists also had low drop numbers and the same skewed ratio? Summary Despite the low numbers of fry at each drop (and the hopefully temporary imbalance!), this is an interesting species to keep, simply because of the limited range of it's distribution. In fact at first I quite enjoyed the smaller numbers as I wasn't over-run with lots of fry that can sometimes be a problem moving on. This particular strain was also much more attractively marked than many that I could find, when doing my checks on this species. Copyright Text and photos. Ivor Hilton. |
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