Live Food for Young Fish

Live Food for Young Fish

Almost every aquarium enthusiast has tried it at some point: breeding young fish. The eggs are hatched with great care and the young fry swim around happily for the first few days. However, many breeders see their young disappear after a few days, often without any apparent cause. Surely you fed them? The problem is usually not the amount of food, but the type of food. Newly hatched fish need very small, suitable food that they can easily see, chase, and eat. And it must be available at exactly the right time.

Fortunately, you can easily grow this tiny live food yourself, without much money or effort. One of the most important first foods for young fish are infusions: microscopic animals that are perfect for the tiniest of mouths. This article tells you how to set up a reliable and sustainable infusoria culture, so you’ll always have a supply on hand when your young fish need it.

1. Infusions (slippers).

Infusoria is a collective term for microscopic unicellular organisms that live in water in which plant material breaks down. Well-known species that are common are slippers (Paramecium), bellfish, radardiae and musselfish. For young fish, these animals are ideal: they are small enough to feed just-hatched young and move actively through the water, stimulating the youngsters’ hunting instincts.

In nature, infusions are often the first food of fish larvae. They are also indispensable in the aquarium in the first days after hatching, especially in species that are born very small such as characids (tetras), corydoras and labyrinth fish.

How do you grow infusions?

Setting up an infusion culture is simple and can be done with everyday materials:

1. Prepare the culture fluid
   Take a handful of dried plant material, such as hay, straw or dried nettle. Boil this in about two liters of water for 10 to 15 minutes. Boiling releases the nutrients and kills germs. Then let the mixture cool completely.
2. Fill the culture jars
   Pour the cooled mixture into glass jars or goblets. This will be the nutrient medium for your infusions.
3. Ent the culture
   Add a little grafting material: for example, sediment from your aquarium filter, mud from a cistern, or a splash of water from a ditch. Wherever decaying organic matter and water come together, there are infusions. This gets your culture going .
4. Culturedevelopment
   The first few days the water will become cloudy due to the growth of bacteria. After a few days it becomes clear again: the infusions have developed and have eaten most of the bacteria. This is when the culture is usable.
5. Maintenance and propagation
   Set up several pots with aquarium water instead of tap water (which may not work as well due to chlorine or other additives). Add a dash of your first culture and feed the infusions with a few drops of milk or a pinch of yeast dissolved in water. When the water becomes clear, it means that the infusions have eaten their food, and you can add a little milk or yeast again.
6. Temperature and conditions
   Infusions are flexible: they grow at room temperature as well as in cooler rooms, as long as there is sufficient nutrition. I myself have had cultures that grew fine at 10 °C in a storage room, as well as those in a warm 25 °C grow room. A pot in which some plant material is constantly present (such as straw), often runs best, although it can start to smell if you don’t change it in time.

How do you collect infusions?

A simple and hygienic way to collect infusions is with a test tube or small vial:

• Place a test tube filled with clean aquarium water in your culture jar, with the opening just below the surface of the water.
• Let it stand for a few hours. The infusions collect in the tube, attracted by the fresh water and light.
• Then empty the tube into the aquarium with your young fish.

You can also use a fine nylon mesh to strain the infusions out of the culture, but often the test tube method is more convenient because you take little turbid water with you that way.

Extra tips

• Ensure continuity: Set up a new culture every few days. This way you will always have a fresh source of infusions available.
• Avoid odor problems: Don’t use too much organic material and change your cultures regularly.
• Alternative food: Infusions can also be fed with a pinch of powdered yeast, instant coffee milk or a drop of diluted fertilizer (only if you have experience ).

Infusions are the perfect first step in raising young fish. They help your little fish get through the critical first days until they are big enough to handle larger foods such as artemia nauplii or micro nematodes .

2. Vinegar nematodes (Turbatrix aceti).

Vinegar nematodes(Turbatrix aceti) are tiny roundworms (nematodes) commonly found in wet vinegar, where they feed on vinegar bacteria. They are about 1 to 1.5 millimeters long and very thin, only 0.1 millimeter across. Precisely because they are so small and agile, they make an excellent live food for young fish that are already slightly larger than the stage where they need infusions. An important advantage is that vinegar nematodes actively move through the water and swim mainly to the surface. This keeps them in sight and reach of the young longer, making feeding more efficient.

How do you grow vinegar nematodes?

Setting up a culture of vinegars is easy and takes up little space. Here’s how to proceed:

1. Prepare the culture medium
   Take natural vinegar, for example apple cider vinegar, and mix it in equal parts with water. For example, for a 200 ml jar , you can use 100 ml of vinegar and 100 ml of water . Add a teaspoon of sugar to this to stimulate the growth of bacteria, which forms the food for the nematodes. As an additional food source , you can add a few small pieces of apple; these serve both as food and shelter.
2. Graft the culture
   Add a grafting portion of vinegar nematodes. If you do not already have a culture of your own, you can often get it from another aquarist, from aquarium associations, or order it from a live food supplier.
3. Let the culture develop
   Put the jar in a place at room temperature (around 18-24 °C). After about a week to ten days you will see that the liquid is teeming with nematodes. The liquid will often become somewhat cloudy, which is perfectly normal. The culture can keep running for months, as long as sufficient food is present and the vinegar content does not become too high due to evaporation.
4. Care of the culture
   Check regularly to make sure the culture still has enough moisture. If the liquid level drops due to evaporation, you can refill a little mixture of vinegar and water. If necessary, occasionally add a small piece of apple or a pinch of sugar to maintain the bacteria population.

How do you collect vinegar nematodes?

The vinegar nematodes swim freely in the liquid, but to feed them to your young fish it is important that you introduce them into the aquarium without too much vinegar, so as not to acidify the water . You can do this as follows:

• Pour some of the culture through a coffee filter or a fine filter cloth (such as nylon mesh). Let it drain for a while so that most of the vinegar liquid drains away.
• Rinse the filter with clean aquarium water or osmosis water to clean the nematodes.
• Then sweep the nematodes with a damp brush or spoon into the aqu arium near the young.

Note that even the finest standard Artemia strainer is often too coarse to effectively stop the nematodes. Therefore, use a coffee filter or fine nylon mesh.

Tips for success

• Multiple cultures: Preferably set up several small cultures at one-week intervals. This will avoid running out of food if a culture collapses.
• Odor: Vinegar nematode cultures have a slight vinegar odor, but generally do not smell as long as you take good care of them and replace the pieces of apple in a timely manner if they begin to rot.
• Maintainability: A well-maintained culture can remain productive for several months. It is wise to start a new culture with fresh ingredients after some time to ensure the vitality of the nematode population.

Vinegar nematodes are a valuable addition to the menu of young fish. They fill the gap between the stage when juveniles need infusions and the time when they can eat larger foods such as Artemia nauplii or micro nematodes . Their constant movement makes them extra attractive and stimulates the youngsters ‘ natural hunting behavior.

3. Micro-eels (Panagrellus redivivivus)

Micro nematodes(Panagrellus redivivus) are tiny, non-parasitic roundworms (nematodes) that are widely used as initial live food for young fish. They are slightly larger than infusions and vinegar nematodes: on average between 0.5 and 2 millimeters long. This makes them ideal for youngsters that have eaten infusions for the first few days and can now handle something larger, but are not yet ready for artemia nauplii.

An important advantage of micro nematodes is that they keep moving for a long time after feeding, which stimulates the hunting instinct of young fish. Moreover, they are easy to grow at home with inexpensive ingredients.

How do you grow micro-nematodes?

Setting up a micro-nematode culture is easy and can be done with ingredients you often already have in your kitchen:

1. Prepare the substrate
   Mix oatmeal or baby flour (semolina or wheat porridge also works) with a little milk or water to make a thick porridge. You can also make a porridge from mashed potatoes or bread with milk. The porridge should be thick, but not too dry.
2. Ent culture
   Put a layer of about 1 to 1.5 cm of this mixture in a plastic container or glass jar. Then add a grafting portion of micro-nematodes. If you do not have your own culture, you can often obtain it from aquarium associations, fellow aquarists or order online.
3. Let the culture develop
   Cover the container loosely with a lid with air holes or with a piece of kitchen paper secured with a rubber band. Micro nematodes need oxygen, so do not seal the jar completely airtight. Put the culture in a place at room temperature (18-24 °C). Within two to five days, you will see the first nematodes crawling up the walls.
4. Care of culture
   • Keep the substrate moist, but not wet. If the culture dries out, the nematodes die. If it gets too wet, it rots and stinks.
   • Add a fresh layer of porridge every few weeks to keep the culture active.
   • Set up a new culture every three to four weeks to prevent the old one from collapsing.

How do you collect micro-nematodes?

Micro-nematodes often crawl up the wall of the container in search of oxygen. This makes collection easy:

• Wipe the nematodes from the edge of the container with a moist brush, cotton swab or your finger.
• If necessary, rinse them in a little aquarium water before you put them in the aquarium, so that you take away as little substrate as possible.

You can feed the nematodes directly to the young fish; they sink slowly through the water and keep moving for quite some time, giving the fish a chance to grab them.

Additional tips

• Use of brewer’s yeast: You can add a few drops of beer or a pinch of brewer’s yeast to the porridge. This accelerates fermentation and promotes nematode growth. Note: Use unfiltered beer (e.g., a Belgian trappist) if you use lager; in many lagers, all the yeast has been filtered out.
• Odor control: Micro nematode cultures can develop a sour or musty odor over time. Keep them clean, set up new ones regularly and discard old cultures before they rot.
• Multiple cultures: Always set up multiple cultures with a few days apart. This way you always have a fresh source of micro-nematodes if one culture suddenly declines.
• Storage: You can put a culture in the refrigerator to slow down the growth process if you temporarily don’t need feed. Then let the culture return to room temperature to resume production.

Why micro nematodes are ideal for young fish

Micro-nematodes fill the gap between infusions/azines and larger foods such as artemia nauplii or micro-worms. They are nutritious, easy to breed and keep moving in the aquarium water for a long time, making them very suitable for small predatory young such as those of live-bearing toothcarps, labyrinth fish and small cichlids.

4. Green Water (Phytoplankton).

Green water is often seen as a problem in the aquarium, but in reality it can be a valuable source of nutrition for young fish. This is because this green, murky water is packed with microscopic algae (phytoplankton). These tiny plants are an excellent first food for young fish, especially for species that naturally grow up in shallow, sunlit waters where algae are an important part of the diet.

Phytoplankton is rich in nutrients such as proteins, fats and vitamins, as well as stimulating the digestion and growth of young fish. Because it floats in suspension in the water, it is easily accessible to larvae and small young that are not yet actively looking for prey.

How do you grow green water?

Growing green water is surprisingly simple. You don’t need any complicated equipment, just some sunlight and a suitable nutrient medium:

1. Choose growing medium
   Fill a large glass jar, bucket or plastic bottle (such as an empty water bottle) with aquarium water, rainwater or osmosis water. Avoid tap water with chlorine or chloramine unless you have treated it beforehand.
2. Add nutrition
   Add a nutrient source to stimulate algae growth. This can include:
   • a few drops of liquid plant food without copper,
   • a pinch of powdered yeast,
   • a grain of fish food,
   • Or a small piece of vegetable (for example, a leaf of lettuce).
3. Light and temperature
   Put the pot on a sunny windowsill or outside in a sheltered spot that receives plenty of direct sunlight. The more light, the faster the algae multiply. In warm weather, development can be visible within a few days; in lower light , it takes a little longer.
4. Maintenance of culture
   • Stir or shake the jar occasionally to keep the algae in suspension and promote oxygenation.
   • If necessary, add a little extra nutrition over time if algae growth stagnates.

Within a few days to a week you will see that the water begins to turn green. The deeper the color, the more concentrated the phytoplankton.

How do you use green water?

When you want to use green water , pour a little of the water at the young fish. Because the algae floats in the water, the young can easily absorb it. Green water is especially useful in species that filter feed or naturally consume algae, such as many species of killi fish, labyrinth fish and certain cichlids.

Be careful not to add too much green water at once: strong algae growth in the aquarium itself can lead to oxygen fluctuations, especially at night when the algae absorb oxygen.

Extra tips

• Multiple pots: Set up different cultures with a few days difference, so you always have a fresh source.
• Temperature: Green water develops most rapidly at temperatures between 20 and 30°C.
• Long-term preservation: Green water has a limited shelf life. You can keep it refrigerated for several days, but freshly grown water has the highest nutritional value.
• Avoid obscuration: Do not put the culture in a place where sunlight is blocked; sufficient light is essential for growth.

Combining green water with other feeds

Green water is excellent when combined with infusions or vinegar algae. The algae remain suspended in the water and fill the moments between feedings with moving, vegetable food. This contributes to a varied diet and supports the development of healthy intestinal flora in young fish.

5. Brine shrimp (Artemia nauplii).

Brine shrimp(Artemia salina) are small crustaceans that occur naturally in salty inland waters and salt lakes around the world. They have been one of the most popular types of live food among aquarium enthusiasts for decades, especially in the form of their larvae: the so-called nauplii. These nauplii are small (about 0.4 mm in size when hatching), rich in protein and polyunsaturated fatty acids, and have a high nutritional value for young fish. Moreover, they actively move in the water, stimulating the hunting instinct of fish larvae.

Benefits of Artemia nauplii

• Excellent nutritional value: rich in proteins, lipids and carotenoids (good for color development).
• Easy to grow: with simple means you can have fresh nauplii available daily.
• Long tradition in aquarium hobby and aquaculture: proven effective for virtually all fish species.

How do you culture Artemia nauplii?

Setting up an Artemia culture is easy. Here’s how to go about it:

1. Preparation of the culture vessel
   Use a bottle, jar or special Artemia culture device (for example, an inverted PET bottle or a conical container) with a capacity of 1 to 2 liters. Drill a hole in the cap for the air hose (or use an air stone) to keep the water constantly moving.
2. Make the saltwater mixture
   Fill the container with water at about 24 to 28°C and add sea salt until you reach a salt content of 25-30 grams per liter (that is 2.5-3% salt solution). Preferably use sea salt or aquarium salt with no additives. Mix well so that the salt dissolves completely.
3. Add eggs
   Add half a teaspoon of Artemia eggs (cysts) per liter of water. Artemia eggs are dry and keep for years. Pay attention to freshness when purchasing; older eggs often have lower hatching rates.
4. Aerate
   Make sure air is continually blown through the water. This prevents the eggs and nauplii from sinking to the bottom and provides sufficient oxygen. Do not use an air stone (or a coarse air stone) to prevent clogging; an open tube is often sufficient.
5. Waiting time
   At optimal temperature and salinity, nauplii hatch after 24 to 36 hours. The higher the temperature (up to 28°C), the faster the hatching.

How do you harvest Artemia nauplii?

1. Stop aeration
   After 24-36 hours, turn off the air pump and let the culture rest for a few minutes. The hatched nauplii usually gather near a light source, while the empty egg shells float to the surface and unhatched eggs sink to the bottom.
2. Siphoning off
   Use a tube to siphon off the nauplii. Siphon them through an Artemia sieve (available commercially ) or a fine filter cloth to catch the salt water. Briefly rinse the nauplii with fresh water to remove excess salt before feeding them into the aquarium .
3. Feeding
   Add the freshly rinsed nauplii directly to the aquarium. Young fish almost always respond immediately to the moving Artemia and eat them eagerly.

Extra tips en variaties

• Enrichment: Artemia nauplii can be enriched for example with spirulina, algae concentrate or commercial enrichment preparations before feeding. This increases the content of essential fatty acids, which is especially useful for predatory fish larvae or breeding projects.
• Storage: Nauplii can be kept in the refrigerator for several hours, but freshly hatched specimens are most nutritious.
• Daily culture routine: Set up several small cultures at one-day intervals so that you have fresh nauplii daily without depending on one batch.
• Clean breeding: Empty egg shells can cause digestive problems if fish swallow them. Try to remove these as much as possible when harvesting.

Why Artemia is Indispensable

Artemia-nauplii are the most widely used live food worldwide for fish rearing in both the aquarium hobby and commercial aquaculture. They are universally applicable, affordable and easy to produce yourself. Young fish grow up noticeably faster and stronger with a diet in which Artemia plays an important role.

6. Water fleas (Daphnia).

Water fleas, also called Daphnia, are among the best-known and most widely used types of live food for aquarium fish. They are small, translucent crustaceans found in a variety of freshwater environments: from puddles and ponds to ditches and stagnant water basins. There are different species and sizes of water fleas, such as Daphnia magna (the larger species) and Daphnia pulex (smaller). Water fleas are popular as food because they are highly nutritious, rich in protein, and also clean the digestive tract of fish by containing indigestible parts that act as “roughage.

An additional advantage: water fleas swim actively in the water, which stimulates the hunting instinct of fish. They are eagerly eaten by both young and adult fish.

Catching water fleas in nature

In nature, you can often find water fleas along the banks of still waters, especially in spring and early summer. When conditions are favorable, they can occur en masse, allowing you to gather a supply that will last for a long time within 15 minutes.

Here’s how to proceed:

• Use a fine scoop net (special water flea net screen or a fine mesh net) to scoop along the water’s edge.
• Collect the water fleas in a bucket of clean water from the trapping site.
• Strain the catch at home to remove unwanted critters such as insect larvae and cyclops, especially if you want to feed the water fleas directly to young fish.

Note: Collect only from places where you are sure the water is not contaminated with pesticides or other harmful substances. Water fleas quickly absorb toxins, which can then be released back into the aquarium.

Growing your own water fleas

Although catching in the wild is easy, self-cultivation offers the advantage of control over the quality and safety of the feed. This allows you to have live feed all year round.

Grow setup

• Barrel: Use a 20- to 100-liter barrel, container or barrel. Many growers use the familiar blue rain barrels, but any clean plastic or glass barrel will work.
• Water: Fill the vessel with old rainwater or osmosis water. Aquarium water that has been standing for some time can also be used. Avoid fresh tap water (chlorine) unless it has been treated first.
• Nutrition: Water fleas feed on suspended particles such as phytoplankton (green water) and bacteria. You can feed them with:
  • Green water (see section on green water);
  • Yeast solution (a pinch of powdered yeast dissolved in water);
  • Finely strained carrot juice, spirulina solution or liquid algae preparations.

Maintenance

• Aerate the water lightly or stir occasionally to keep the nutrient particles in suspension.
• Feed sparingly to avoid water pollution. Food that is not eaten, can lead to bacterial outbreaks and population collapse.
• Change some of the water (10-20%) if it becomes cloudy or develops an unpleasant odor.

How do you harvest water fleas?

• Use a fine net or strainer to scoop out the water fleas from the vessel.
• Rinse them briefly with clean aquarium water to remove excess food and any debris.
• Sort by size with a sieve when feeding young: small fish cannot handle large water fleas and may even choke on prey that is too large.

Extra tips

• Cyclops and other bycatch: Be careful not to feed adult cyclops to young fish; they may attack young. Strain your catch carefully.
• Multiple cultures: Set up several barrels with a few days difference, so that if a culture collapses you always have a reserve.
• Seasonal influences: Growing outdoors is often easiest in spring and summer. Indoors can be done year-round with a grow barrel by a window or with artificial light.

Why water fleas are valuable in the aquarium

Water fleas are not only an excellent food source, they also help absorb excess food and fine particles from the aquarium (they filter the water, so to speak). Plus, you’ll see fish visibly perk up from chasing these prey. It is one of the most natural foods you can offer your fish.

7. Cyclops (One-eyed copepods).

Cyclops is a collective name for small copepods found in freshwater throughout the world. They get their name from the fact that they have a distinctive single eye spot (ocellus) right in the middle of their heads. Cyclops average 0.5 to 2 mm in size and have an elongated body with two segmented antennae with which they move jerkily through the water. Their erratic swimming movements make them attractive prey for many fish.

Cyclops are an excellent source of live food for medium and adult fish. They are rich in protein and are often high in carotenoids, which can contribute to the color development of your fish.

Cyclops as a feed: advantages and concerns

Cyclops are nutritious and stimulate the natural hunting behavior of fish. Nevertheless, they are less suitable for newly-hatched fish. This is because adult Cyclops can hunt by themselves and tend to grab and eat larvae and young fish. Therefore, it is important to feed Cyclops only to fish large enough to overpower these crustaceans on their own.

With young fish you can use Cyclops nauplii . These are much smaller and pose no threat.

Where do you find Cyclops?

Cyclops live in a variety of stagnant or slow-flowing freshwater environments:

• Pools
• Ditches
• Rain barrels
• Ponds

When scooping live food from nature , you often catch Cyclops along with Daphnia and other planktonic animals.

Cyclops breeding

Although Cyclops are usually harvested from the wild, you can also grow them at home:

1. Grow vessel
   Use a small aquarium, bucket or clear plastic container of 10-20 liters.
2. Water
   Fill with old aquarium water, rainwater or osmosis water.
3. Nutrition
   Cyclops filter fine suspended food such as micro-algae and bacteria. Feed them with:
   • Green water (phytoplankton)
   • Fine powdered spirulina (slightly dissolved)
   • A weak yeast solution (be very sparing to avoid contamination )
4. Conditions
   Place the culture in a bright spot at room temperature (18-24 °C). Aeration is not necessarily necessary, but occasional stirring helps to keep the nutrient particles in suspension.
5. Harvesting
   Scoop out the Cyclops with a fine net. If you have young fish, you can strain the harvest to feed only the nauplii.

Practical Tips

• Sort by size
  Use sieves with different mesh sizes to separate nauplii from adult Cyclops. Nauplii are safe for juvenile fish; adult Cyclops are not.
• Limit feeding
  Feed small portions of Cyclops into the aquarium to avoid leaving too many behind, as live Cyclops that are not eaten can hide and later attack your young fish.
• Prevent collapse of the culture
  Change some of the water in your culture tank regularly (10-20% per week) to avoid accumulation of wastes.
• Use in moderation from nature
  If you take Cyclops from nature, make sure your catch does not contain predatory insect larvae (such as water beetles or dragonfly larvae) and that the water is clean (not contaminated with pesticides or fertilizers).

Cyclops in aquaristics

Cyclops are a valuable addition to the diet of fish that are somewhat larger, such as juvenile cichlids, labyrinth fish and larger livebearers. Their lively movement encourages fish to hunt, which stimulates natural behavior and prevents boredom.

Author

Ronny Dhuyvetters

Post-processing

John de Lange