Feeding Egg Layer Fry

Egg Layer Fry are Almost Microscopic, so what to Feed them?

Tiny Egglayer Fry Need Special Foods
Thomas R. Reich PhD

One of the biggest reasons beginning breeders lose their first few attempts at raising most fry from the successful breeding of egg laying fish is that the inexperienced breeder has not prepared the proper food in advance for the new hatchlings.  Once newly hatched fish are free swimming they must be fed within hours or will die of starvation.          

Once a Fish is born or hatched, and once it has become free swimming, it must have food available immediately or it will most surely die within hours.  Live bearing fish fry take food almost immediately, eating finely ground dry food, baby brine shrimp or anything they find.  What makes Guppies, Mollies, Platys and other Livebearers so great as first breeding projects, is that you will actually see them gnawing on the edges of large flakes of adult flake food right after birth!  Livebearer fry are built to survive in the aquarium environment, and success raising the fry comes down to the basics.

On the other hand, most egg laying fish fry are quite different; they are born into the wild under much different circumstances.  Where the average livebearer lives in lakes and its young hide in plants self sufficient from the second they swim from moms body, the fry of egg laying fish span a wide spectrum from eggs cast out into the vast unknown of a flowing river, to those laid into sophisticated nests and cared for by dodging parents until maturity.

When any egg hatches it is different from when a live fish is “born”, when an egg hatches, the yolk, or food source is still attached to the fry.  This “yolk” feeds the fry for as short a period as 24 hours and as long a period as 4 days.  With Cichlids and parental nesting fish, you will see the adult fish moving the fry from place to place throughout the aquarium during this period.  This serves 2 purposes in the wild, one is to keep fungus from forming on the helpless fry, the other is to avoid predators of all types large and small, in the wild even insect larva such as hydra are a danger to the tiny fry.

As soon as the fry are free swimming, the adults herd the fry or brood to food, in the aquarium you will see them leading them or pushing them from place to place.  One problem however, you keep a very clean aquarium, so the natural food of the fry is virtually not present in large enough amounts to feed the fry and they will die.  The first food of most hatchling fry is Infusoria, a microscopic bacterium that grows on rotting plant matter, found in streams and ponds, but usually not present in great quantity in your aquarium!

You must provide this “Infusoria” for your fry.  It becomes even more of a problem when breeding Characins, Danios and Barbs, we teach you to do so in almost sterile conditions, so there is 0 Infusoria present, and the fry of these fish are half the size or less of that of the cichlids so the need of Infusoria is even greater the first week.

After you can clearly see the fry with the naked eye swimming about freely and strongly, they are ready for a second stage food, special prepared egg yolk, extremely ground dry foods, baby brine shrimp and later daphnia and other fun varieties of foods high in protein.  Protein is the key to fast growth, small quantities of a varied diet frequently throughout the day, frequent partial water changes to keep the excess food and waste removed, will gain you fast growth and healthy fish fast!


RULE # 1:  One day without food in the first 2 weeks of a fry’s life and it will die

RULE # 2:  After the first 2 weeks, the fry will live through anything but foul water and over crowding

RULE #3:  If the water gets cloudy this is actually food, Infusoria appears as cloudy water, stop adding it for a short time and the fry will eat it

RULE # 4:  Once you master Feeding Fry, you have mastered the most difficult part of the breeding process of any fish.


How to Prepare and Feed Fry Food


Infusoria Method 1:

Whether collected or cultivated, it is a necessary food for baby fish not large enough to take daphnia or baby brine shrimp.  Cultivation is comparatively easy, usually accomplished by putting lettuce or spinach in a small tank with several snails.  Allow greens to decay.  The snails eat the greens in this state and their droppings result in the development of the most pure of Infusoria.  Most greens, in a decomposed state, will produce some type of Infusoria with or without the snails, when the water becomes slightly white cloudy, this “cloudiness” may be in part the Infusoria, put small amounts of it in the tank with the fry with a “turkey baster”


True Infusoria Method 2 for Serious Breeders: 

Though this method takes time and space, if you really want to be a serious breeder, with truly successful results, I am talking about breeding the Neon or the Rainbow successfully, pay attention.  This is the method used by fish farms, and it is the only true way to create a stable Infusoria culture that will keep those fragile fry alive and growing from day one.

When commercial breeders knew they needed to raise thousands of fry to maturity fast in order to run a successful tropical fish wholesale business, they knew Infusoria had to be reduced to a science.  A steady supply had to be provided and had to be ready whenever the fry hatched and became free swimming, there is no exact timing to nature after all.

Since it is almost impossible to rear large numbers of fry without a good infusoria culture, it is important to study in detail the principles involved in making such a culture.  Infusoria gets its name from heterogeneous a collection of organisms (mainly protozoan), which develop in an infusion of hay or other suitable organic matter.  These minute organisms constitute an ideal first food for the fry of much egg laying fish.

Infusorians are organisms which live in water, feed on bacteria, utilize oxygen, and thrive at temperatures between 60 F and 70 F.  The first task then is to provide a culture medium where some organic material is allowed to rot, for this will produce the bacteria needed by the infusoria.  This should be carried out in a fairly large container with a good air-water surface so that plenty of oxygen is available.

The manner in which this culture is made is quite simple.  A whole large lettuce is broken into small pieces and placed in a fish tank or a plastic tub of about 10 to 15 gallon capacity (plastic storage container from big box store can suffice). A gallon or so of boiling water is added and the whole allowed to stand for a few hours.  After which about six gallons of tap water are added.  Aquarium water should not be used for this purpose for if it contains some Cyclops or Daphnia.  They will feed on the infusoria and soon you will have a culture of these organisms and no infusoria.

It is recommended to stir the contents of the tank or tub two or three times a day and observe the changes that occur.  By about the third day the water will have become turbid and will have a distinct odor.  This is due to the growth of millions of bacteria in the culture medium.  They hatch and begin to multiply in the medium.  The infusoria feed on the bacteria and multiply at a rapid rate.  As a result of this the population of bacteria declines and by about the 10th day the culture becomes quite clear, and virtually odorless.  By about the 20th day the culture will be really thick with infusoria and stable for feeding fry. 


USING THIS METHIODS FOR JUST ONE BREEDING:  For a small amount of infusoria culture, a little hay (available at most pet stores) or a banana peel, eather covered with boiling water in a quart glass jar and allowed to cool before adding tap water to top of jar, then allowing to cycle for the same 20 days will produce the same results.  However, this makes a very limited amount of Infusoria, so it is for a very small brood.  The same method could


WARNING:  A proper culture of Infusoria should not have a foul odor, very cloudy foul-smelling mass of water indicates a high bacterial content, in fact a state of pollution.  If such water is poured into the tank containing fry there will be little for the fry to feed on and they will perish either from starvation or the pollution that will be created by such a procedure.


A foul smell in a culture indicates that anaerobic conditions prevail, favoring the growth of anaerobic bacteria which produce hydrogen sulphide.  If this is noted, the culture should be stirred more frequently or mild aeration applied for a day.  Remember that infusoria need oxygen and anaerobic conditions will impede their growth and multiplication; Many infusoria cultures fail because of too low a temperature, so this point should be checked also. 


THE FINAL SUCCESSFUL INFUSORIA PRODUCT:  Successful fish breeding commences with learning to produce good thick cultures of infusoria.  The final product should be virtually as clear as aquarium water and teaming with thousands of organisms.  The trained eye can see them clearly if a glass jar full of culture is held so that light strikes from one side.  A hand lens giving about five power magnification is useful and all that is necessary to see just how active the culture of Infusoria is.




BABY BRINE SHRIMP:  Newly hatched brine shrimps are readily produced from the small brown eggs of Artemia salina, which can be purchased in most aquarist shops.  It is the ideal first food for the fry of livebearers, Cichlids, and other fish (e.g. some Barbs) which produce fair-sized fry.  It is also the ideal second food for fry that passed infusoria stage.

The method of culture depends largely upon the amount of newly hatched brine shrimps required per day.  The basic principles however are the same.  A quantity of brine to hatch the eggs in is needed and an adequate supply of air should be supplied to keep the hatched shrimps alive, until they are needed.  Three methods of culture are in common use.  These are 1) The jar method; 2) the pan method; 3) the inverted cone method.  The brine used in all these methods is prepared by dissolving six tablespoonfuls of sea salt to each gallon of water.


MICROWORMS:  This food is only slightly larger than brine shrimp. It can substitute for the shrimp or better still can be used in conjunction with the baby shrimp for a varied diet and to assure a consistent and unbroken food source of live and ready food.  A varied diet is also more conducive to speedy growth of the fry.

To culture this food, obtain a small plastic container (similar to Tupperware) and roughen the sides slightly by rubbing with a very fine grade of emery board or sand paper.  Now put in a one inch deep layer of fairly stiff, well cooked oatmeal.  Smear the surface liberally with a culture of microworms obtained from a local pet store, or a reliable on line source, cover the dish to cut down the light reaching the culture and to prevent it from drying out.  Make an air hole in the center of the lid, not the edges but the center.  Stand in a warm place, 70 F to 74 F. 

If you hold the culture up to the light in 2 or 3 days you will see the whole surface shimmering with the movement of enormous numbers of worms inhibiting the surface.  In a week or so the worms will migrate as a sheet from the culture up the sides of the container. 

It is customary to remove the worms from the sides by wiping them off with a finger (yuck!) which is then dipped into the fry tank to release the worms.  Not only is this not a pleasing prospect, it is not safe for the fry, there may be contaminants on your finger, under your finger nail.  I have a better way, use the edge of a small piece of suitably shaped styrofoam, make sure it is clean unused and has never touched chemicals of any kind.  This will keep your finger clean, the fry and the microworm culture uncontaminated.


GREEN WATER:  Another food for fry, easiest way to create this “green water” is in the summer, simply fill a large glass vase with aquarium water, place in the sun and wait a week or so.  When the water turns green this is an form of algae that is single celled microscopic and part of a varied diet for your fry.  Not necessary but another fry food just the same.  Feed by turkey baster very sparingly.


FINELY GROUND DRY FOOD:  As the fry age, you can start to feed them protein rich dry food, but it must be very finely ground, such food if available at your local pet store or on line under the name “fry food” or “first food”. 

Another way to get a finer grade of dry food quickly from flake prepared foods is by grinding them in a pepper mill or crushing the prepared food between flat tiles and then sieving carefully.  Such food for young fish may preferably contain more animal material and may be made from 100% dried shrimp or crab if you can pick from a variety of prepared food to grind.


EGG YOLK:  hard boil and egg, cool completely remove the yolk (the yellow part) but the yolk inside an nylon stocking or piece of cheese cloth and squeeze the egg yolk through it, take a very small portion, that that would fit on the end of a pencil, and put it into the fry tank, it will disseminate into tiny particles and again be a part of a varied diet.


FINAL NOTE:  Remember to siphon off all uneaten food from the bottom of the fry tank.  Uneaten food will quickly rot and foul the water, week old fry are very susceptible to foul water, which lowers the oxygen content of the water and will kill the fry in quick order.  Remember you cannot have regular filtration during this very young period, so get what is called a sponge filter at your local pet store or on line, this will help you keep the water from fouling.