Guppy Fry Needs

Raising Fry, The Guppy Fancier's Number One Obsession!

Young Fry Feeding Fry

New-born fry have tiny mouths and huge appetites! They empty their stomachs every 20 minutes! Of course, it is not wise or feasible to feed them this often. Feed your guppy fry 4 to 8 times daily.

When feeding fry it is important to offer a variety of food. A couple of quality, high-protein flake foods should be given, crushed up finely. Flakes are an excellent food just before lights out. Also, some breeders like to feed a small amount of flakes before each feeding of BBS. They believe that it helps the fish reap the benefits of BBS by keeping it in their systems longer with the staple mixed in. Unfortunately, BBS does have a laxative effect.

Baby Brine Shrimp (BBS)

This is generally accepted as the #1 food for guppy fry. If you have a large guppy-breeding operation, you will want to give them the ultimate - live BBS that you have hatched yourself. If however, you are carrying on a small hobby, look for the convenience of frozen BBS. Make sure though, that it is BABY Brine Shrimp, not Adult Brine Shrimp. BBS has much more nutritional value than Adult Brine Shrimp (ABS) and can fit into the fry's tiny mouths. Remember, anything that is too large for fry to eat will go uneaten, wasted, and it will pollute the tank. The bonus in serving up live BBS is that what is not eaten immediately will survive and be consumed later. Be conservative and keep a watchful eye when feeding frozen BBS since it will rot quickly if not eaten right away.

Egg Yolk

Another good fry food that you probably have in your refrigerator right now is egg - specifically the yolk. It can easily be made into a paste that is simple and inexpensive. It is a great source of protein that is eagerly consumed by fry and adults alike. Simply take a hard-boiled egg and remove the yolk. Place it in a small, re-sealable container and add a few drops of water while mashing it with your finger or a spoon. When made into a paste you can feed TINY amounts to your fry. It creates a cloud of protein for them which they will devour. If you feed too much, however, you will foul your guppies' tank. You can feed them yolk twice a day. Adults will enjoy some egg too, but use less water to create chunks for them to eat. Liquid fry foods are also available in tubes similar to toothpaste. Use sparingly, as it can easily pollute the water.


Oatmeal Microworms

Microworms can easily be cultured and fed live, an excellent food and a low-cost alternative to BBS, however many breeders like to continue feeding BBS in addition to microworms for variety. 

They are thread-like worms imported from Europe which are tiny enough for fry.  I use oatmeal or mixed baby cereal as the culture medium which is very nutritious -- healthy worms means healthy fish food!  Microworms do not crawl very high on the sides of a container and are easily contained.  There are many ways to harvest them, however, as seen above, I lay pieces of rough scrubbing pads on the cereal and swish them in a jar of water with a popsicle stick.  The worms, which have crawled onto the popsicle stick and pads, fall to the bottom and any cereal will rise to the top.  Just pour this off a couple of times and the worms will be clean. 

Fry will grow more quickly initially with microworms and get about a 2 week head-start over fry fed BBS, although they will eventually catch up. However this growth spurt is important and helps in fighting off diseases. Microworms will remain alive much longer in a tank than brine shrimp, and do not swim away from the fry. These tiny worms are also much easier to culture and handle than BBS and after you have a culture going it can last indefinitely. Although this food is best fed to fry, all guppies will benefit.  Feed sparingly to adults. 

To learn more about microworms, go here .


This is popular, easy fish food.  Also known as "water fleas", there are magna and pulex varieties.  Magna is a bit larger and more suitable for guppies.  The best culture is green (algae) water.

Vinegar Eels

These are very tiny nematodes and only suitable for young fry.  They can be found in unpasturized cider vinegar, or cultures can be purchased.  Simple and easy to "grow": all that is needed for a culture medium is cider vinegar, an apple, and water.

Further information on feeding the larger guppy can be found on "Feeding the Growing Guppy" on this site.

Fry Tank Maintenance

A good temperature for fry is 80F, which gets their metabolism in high gear.  However, this is not a necessity -- mid 70's is sufficient.  At the higher temperatures, they will eat more and grow faster. This is important when you are born so tiny! After all, the bigger a fish you are, the better off you are in the fight to ward off parasites, disease, and, oh yes, bigger, hungry fish! 

All this adds up to more work on the guppy keeper's schedule, for:

Fast metabolism + heavy feed schedule = frequent water changes!

First of all, this depends on the number of fish per gallon of water. Fewer fish mean less maintenance, basically. The best home for a batch of fry is a 5-gallon bare-bottom tank. It is not too large for them to find the food, and not so small that it allows for a stable, clean environment with a small inside box filter.  Changing water at a rate of 50% a week keeps the water quality high, but make sure the replacement water is properly conditioned to remove chloramines and chlorine, and has the same pH and temperature as the tank water, so as not to shock the tiny inhabitants. Some guppy breeders do up to 100% water change will no ill effects.

Water changes themselves seem to spur growth. Nitrates building up in a tank seem to naturally slow the growth of most fish. This is likely a result of the natural order of things. Too many nitrates indicate that there is a population explosion, and slows growth in fish to make up for this. The only way to remove nitrates is through water changes.

Lighting is also an important aspect in the growth of guppies.  Many breeders keep the lights on anywhere between 12-17 hours.  Strong bright lights are not necessary, but guppies that live in a dim tank will often form deformities of the spine.  Lights should not be kept on around the clock so that the fish can rest and relax for at least 7 or 8 hours.

Remember that the first few months of a guppy's life are the most important. Fancy guppies are not solely nature's creation. People bred them to be as beautiful as they are and the only way to make your guppy become the best he can be is to give him the best food and best water.

See Tank Maintenance for more information on tanks and water changes.

Approximate growth rates of the Guppy.

Please keep in mind that this will vary according to care (especially feeding), and genetics. However, I have included this for general reference. Please note that females may grow much larger than the males.

Male Body length not including tails.

  • New born: 6 mm
  • One Week: 7 mm
  • Two Weeks: 1 cm
  • One month: 1.5 cm
  • Two months: 2 cm
  • Three months: 2.5 cm
  • Six months: 3 - 3.3 cm
  • Full grown: 3.5 - 4 cm

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