I gather that your guppy baby food doesn't list ingredients. Probably a small package. Chances are that it includes animal and vegetable material and is reasonably well balanced. I would bet a modest sum that it will also have cereal fillers.

Would the same company/ marketer also offer a guppy flake mix? What does it say are the contents? If the packages don't list ingredients, would the company's web site do so?

Guppies are browsers and nibble at algae when nothing else is available. Since they seem to need the veggie content and may pull microscopic critters from the algae, those are not bad things. And better occupied, they don't spend so much time writing graffiti on the aquarium's walls. ;)

I have a hard time believing that your guppies would resist a good frozen food (defrosted in Luke-warm water, run through a sieve or fine-meshed net to remove the organic soup, which often accompanies frozen foods, and then fed with a turkey baster from a jar of clean water) or especially live food. If they do ignore clean bloodworms or brine shrimp or glassworms, "fast them" or don't feed them for a day or two. They may be easy to ignore on a holiday like today. ;)

Usually the difficulty aquarists have in feeding frozen or live foods is that spme fish may get spoiled and then turn their noses up at flake foods! Weaning fry off of newly hatched bbs may involve not feeding them for a day and then introducing the fine flake fragments or a especially prepared fry food.

Done carefully, even young piranhas can be trained to take pellets as opposed to disease ridden feeder goldfish.

Another trick here is to introduce a similar sized fry, which already eats flake fragments and which can be told apart from the fish being conditioned to the flakes. I could recommend guppies, mollies or Endler's livebearers (but not in a guppy tank). In killie tanks, killie fry such as Fp. gardneri or Ep. dageti (or again guppies) can be introduced into a tank of fry from a different genus. Even annual fishes such as Nothobranchius can be trained to subsist on flakes.

As Scott L. has suggested, a greater variety of foods is even more beneficial that just feeding a flake mix, even if the flakes are an excellent food by themselves. (And all prepared foods today are better than the rice flakes of 60-80 years ago!)

Frozen and meaty foods obviously have a much greater water content then prepared stuff. But they also may have trace elements and especially vitamins lost as flake cans are left open. There will be a correlation between the number of eggs or fry, the size of the eggs or fry and the health of the eggs or fry produced by whatever species being spawned and the amount of live food in their diet.

We visited a small zoo yesterday in Aurora, IL. Their reptile house was something I had never checked out. It was bright and clean, seemingly well kept and the animals (many of them refugees from pet owners who had no idea of the eventual size or life expectancies of their charges) looked great.

I had to smile, while chatting with a keeper of them. We were observing a bunch of eastern painted turtles and a lot of red-eared sliders. A nearby map indicated that the sliders' natural range extended to northern Illinois, something I was unaware of though we have long had abandoned (former pet) sliders in local lakes and ponds.

Admitting to my ignorance in sorting males and females, I asked if the shape of the shell was an indicator. The girl (ok, probably 25 and a recent biology degree graduate, that age description prolly puts me in perspective) laughed and noted that shells, except for larger size, weren't going to offer much of a hint as to a slider's gender. However females were often considerably larger than males and the males seemed to "know" that larger females produced more eggs and that the eggs would be a little larger than those produced by (the usually ignored) smaller females. Couldn't help thinking about the parallel with guppies, at least wild ones.

Studies have shown that wild male guppies prefer the bigger females, presumably on the basis of those female's ability to produce more fry and maybe even slightly larger fry. (And if there are not large predators around, there is a female guppy preference more the more colorful males who also happened to be the "best dancers" maybe because those things indicates greater health and vitality among the males. Female guppies seem to shun male guppies with gill flukes.

The reptile house keeper also noted that one could look at those green turtle's claws (fingernails?) and that the males would have obviously longer ones. They used those to caress the female's cheeks (sides of the head anyway) and to stimulate them to mate. Armed with that knowledge, it was easy to spot the males.

And on cue, a male slider, about half the size of a female, swam up to her under water and began stroking the sides of her head! A couple of other smaller sliders were jostling each other behind him to get in line!

If an aquarium fish is well fed and cared for and in a comfortable environment, they will usually wish to procreate. If that is true for turtles too, then they were very well cared for. :)

By the way, many turtles need a combination of animal protein and plant material too. And proportions of each may vary by the turtles' age.

Back to the live fish food. Frozen brine shrimp may actually have more nutritional value than the live stuff at shops, because the live shrimp may have been unfed for a week. (Though if you Google gut-loading, they may be used to bring dietary supplements like Selcon to your fish.) Presumably the shrimp that were frozen were better fed at the time of processing.

If one doesn't have a municipality, which bans open water containers, one can raise live foods in a shaded, out of the way corner in their yard. I prefer to raise Daphnia (which eat all sorts of things and are easy to raise outside and even indoors. Daphnia can also be gut-loaded and can live, reproducing (usually just females parthenogenically), almost forever in an aquarium if it doesn't have a power filter or too many hungry mouths. The problem with raising food outside is mosquitoes, although I can't think of a food, which elicits such a strong feeding response from most small fishes! In this age of dog heart-worm disease, St Louis encephalitis, West Nile virus (though mosquito-born malaria probably killed 10,000 times more people world-wide last year) it does make good practical and moral sense to either raise and harvest all the "mossies" or not raise any at all.

For a way to raise and harvest all of a batch, please see
http://www.aquarticles.com/articles/management/Davis_Mosquitoes.html

If one is raising Daphnia and wants no mosquitoes (or probably bloodworm or glassworm larvae) in that culture, an appropriately sized piece of mosquito dunk may be added to the half-barrel or container used. More on that and culturing Daphnia can be found Google-searching Guppylog.

Just yesterday I posted suggestions to both the NANFA-L and the Livefoods e-mailing lists a little bit about avoiding predators in outdoor cultures and mosquitoes. The latter (smaller) post was archived at http://fins.actwin.com/live-foods/month.200807/msg00002.html

NANFA (North American Native Fishes Association) has an excellent archives. But they take a while to archive everything.

One  also can search at
http://fins.actwin.com/search.cgi

or even Google search Guppylog for a lot more on live and frozen foods.

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A note on the deletion of the reply way above. I accidentally posted there and then saw some (massive) need to edit the thing. If (having editorial rights) I just deleted that post completely, it would have also taken out all replies afterwards. But there is a "suppress comment" option usually used to eliminate comments by spammers that leaves later comments. So that comment was removed and hopefully the immediately above comments are a little less incoherent. ;)