Grindal worms (Enchytraeus buchholzi) are one of the best live food sources for feeding aquarium fish. It is too easy to culture these worms in large quantities. Also, grindal worms are a very nutritional live food source for aquarium fish. They have a nutritional value of about 70% protein and 14% fat. That makes them a valuable addition to an aquarium fish’s diet. Additionally, due to its rapid and continuous multiplication ability, it is widely cultured and used for feeding aquarium fish.
What are grindal worms?
Grindal worms (Enchytraeus buchholzi) are first described by František Vejdovsky in 1879. They are small and white non-parasitic enchytraeid oligochaete worms. The scientific classification probably covers a group of small and morphologically indistinguishable worm species that live in soils across the globe. The name grindal worm comes out later when it was beginning to use in the aquarium hobby. Mrs. Morten Grindal of Sweden, who was working on improving the culturing techniques for white worms was the first aquarist to isolate this smaller species. After her studies, these worms are called grindal worms in the aquarium hobby.
Grindal worms are very similar to white worms but their size and care differ. Their size is smaller than white worms and can reach around 10 mm long. Therefore, grindal worms are a suitable food source to feed larger fry as well as adult fish. While maintaining and culturing white worms require lower temperatures, grindal worms can tolerate higher temperatures up to 26-28 °C. Even though, the optimum culturing temperature reported is 20°C for the grindal worms. Grindal worms can reach maturity at 16 days and reproduction begins at 16-20 days after they hatch from eggs. While culturing the maturity period must be considered accordingly.
How and Where to Get the Starter Culture?
For culturing the grindal worms, it is necessary to obtain the first starter culture. There are two options for getting the starter culture. The simplest way is getting the starter culture from a seller that already has an isolated culture. Just find a seller. Pay the money and receive the culture and that’s all.
The other way is isolating the starter culture yourself. Since they exist almost everywhere, it is easy to collect your worms to start a new culture. In the following sections, we will dive into the details of collecting and isolating the worms.
Where They Live?
The best place to find the worms is the gardens. Since they eat decomposing plant and animal matter, they mostly live and exist around the trees, plants, and bushes. The most significant point for finding them is moisture. It is easier to find them at places that have regular irrigation. They can smoothly move and eat in the moist soil, so they prefer to live in such places. But it is not mandatory. You can create a moist place to collect grindal worms. First chose a place such as under the trees, bushes, or near the garden plants. Water the selected location and cover with a dark-colored plastic bag or wrap. That will also prevent the light pass through. Keep watering the same place for the following few days and keep it covered. The worms will start gathering in this moist place after a couple of days.
How to Collect Grindal Worms?
The most significant point is to find the proper place to collect the worms. After finding, or preparing a suitable place to collect grindal worms, there are too few things needed. Also, the worms will still be scattered around in the soil. It is necessary to bring them together more densely. To do so, we need to attract them to gather at the collection area by using bait. The best bait to use is a slice of bread since it has a sponge-like structure and more stable that won’t easily break down on the soil. Apart from the main bait, a small amount of milk, a pinch of baker’s yeast, and a plastic bowl to cover the bread are all.
After bringing all the materials together, we need to prepare our bait for the catch. Start with cutting the edges of the bread. Then, pour the milk into a plate and dip the bread in to saturate the bread with milk. Later, sprinkle a little dry yeast on one side of the bread. Also, after dipping the bread in the milk, you can use some yogurt before adding the yeast. But it is not mandatory.
Now our bait is ready for the catch. The following step is to water the soil one last time and let the soil fully absorb the water. Then place the bait over the soil with the yeast sprinkled side touching on the soil. Cover the bowl over the bread and put some weight over it to prevent other animals reach or eat the bait. Keep the bait covered for the following 3-5 days and let the grindal worms gather around the bait. For keeping the soil moist, it is better to cover the soil surface with an additional plastic bag or wrap. Checking the bait every 2 days and misting to prevent drying out will improve the starter culture yield. Also, it will enable checking for the worms gathered around.
During these regular checks, if the number of the worms reached around a hundred, it is enough to start a culture. For collecting them, it is better to take the bait out with the soil around since there will be worms in the nearby soil. After transferring the bait with soil and worms, try separating the bait and the worms on it. Afterward, dispose of the waste bait and keep only soil and worms. Now the harvested worms are ready to use as the starter of the first culture. In this first culture setup, some other creatures may come out apart from the grindal worms. So, it is better to use this first culture to grow worms and isolate them for the following new clean cultures.
Preparing Grindal Worms Culture Medium / Bedding
Grindal worms live inside the soil in their natural habitats all around the world. They can live in various soil types such as sand, peat, clay-based soils, coco peat, etc. But culturing and using them as live food with mass production requires providing the optimum conditions to the worms.
The optimum bedding or the medium for the culture needs to provide the worms a comfortable living and breeding environment. It needs to be loose, and light-weighted to let them move around smoothly for feeding and breeding. Suck kind of bedding will also serve as a proper cover from the light. Additionally, the medium needs to contain some plant matters that the worms are feeding in their natural habitats. Therefore, the best options for a grindal worm culture medium are potting soil and coco-peat. The critical point of choosing the proper medium is to pay attention to the content of the soil. If the soil contains chemical additives, these chemicals may kill the worms. Therefore, try to select plain and natural soil as a culture medium.
A proper medium for culturing grindal worms must be capable to absorb the water and stay moist for a long time. Also, after losing its moisture, the medium must still be loose. To find the proper medium for the culture may take several trials with different brands and sources.
Another point to pay attention to is the possible intruder contamination due to the culture medium. If the culture medium contains some bugs or, insect eggs they may compete with the grindal worms or harm them. Therefore, the source of the medium is significant and must be selected accordingly. But there is a method to eliminate the pests for small amounts of mediums. It is microwaving the bedding medium before setting up the culture. Just put some medium in a proper container and microwave it for few minutes. Check the medium regularly if it is highly heated and Voilà!
Setting Up the Grindal Worm Culture
After getting the starter culture and the culture bedding, we need to add up both in a container that will keep our culture clean and tidy. The culture container with a lid is more suitable than an open container for culturing grindal worms. The cover needs to be in a proper type to keep the culture away from pests and bugs. So, it must be tightly closing the container with no gaps. On the other hand, opening a vent on the cover will improve culture yield and extend the culture lifetime. But it is significant to avoid pests entering the culture. Therefore, after opening the ventilation on the cover, it must be properly sealed with a strainer that will ensure airflow but also keep the bugs, insects, larvae, and their eggs out of the container. The strainer can be as simple as a paper towel, or a fabric cloth glued over the vent.
Preparing the culture bedding before putting it into the culture container is a better practice. It will help to ensure the moisture level of the bedding.
For preparing the culture medium, put some peat or garden soil into a plastic container. Add water and make sure that the peat is saturated with water. Afterward, pour the wet peat on a cloth and squeeze it to remove excess water. Be sure that the peat is wet but not slushy. If the peat is slushy, the worms will try escaping from the bedding or drown.
After preparing the bedding medium, transfer the moist it into the culture container. Spread and crush the moist peat by hand while equally distributing it in the container. Later, gently press over the peat to flatten the surface and add the starter culture or the worms over it. Now, the culture is ready, and it is time to feed the worms to breed them in large quantities.
How to Feed Grindal Worms
Feeding grindal worms are the easiest part of culturing grindal worms. They almost eat everything organic. This means most kinds of plant or animal substances are suitable for feeding them. But mostly, they are eating vegetable-based substances and more specifically the cereals.
Feeding the worms with cereals has advantages while compared to feeding them with meat-based substances. At first, it is more economical to use cereals for mass cultures. Also, it is more sustainable in terms of the service time of the culture. While feeding the culture with cereals, there will be less soil toxification caused by the digestion and degradation of wastes. Therefore, the service time of the culture will be longer than feeding the worms with foods containing animal substances.
On the other hand, there is a process called Gut loading. Gut loading is a process by which live food is raised and fed nutritious foods to pass those nutrients to the animal that is intended to be fed. Feeding the grindal worms with a carnivore diet balanced with cereals increases the nutrition content of the worms. Despite reducing the service period of the culture, this will also increase the nutrition content of the live food and increase fish growth and health. For gut loading, the most suitable foods are dry kitten and puppy chows. Pellet, tablet, or flake fish foods are also suitable to use feeding the grindal worms. But the most significant point on that is feeding the culture with a small amount of food. Then observe if the worms are consuming it and replace it after 2 days. Otherwise, the leftover food will crush the culture too fast. Also, observing the consumption of the worms on different foods will provide feedback to select the best food for feeding the worms.
How to Harvest Grindal Worms?
Harvesting grindal worms is an easy task if you are using the proper tools and methods. Since they are gathering around the food, it is best to use this behavior to easily harvest them. While doing this, it is also substantial to harvest the worms in large amounts and leave the culture medium, or the debris behind. To do so, we will use some basic tools that will work great for harvesting grindal worms.
Typically, the best tool for harvesting the worms is a flat plastic or glass plate that will be located over the food. It is a better option to use a plastic plate instead of glass since the glass is heavier and will reduce the mobility of the worms. Using a plastic wire mesh, plastic sheet, a thin plastic plate or glass will work well. The worms will gather around the food and climb on the plastic sheet or glass placed over the food. Afterward, to harvest the worm, just lift the plastic sheet or plate, remove any food or medium residue with a cotton bud then dip it in a cup of water. In this way, the grindal worms will pass to the container from the harvesting sheet. Later, by using a pipette or a small turkey baster just squeeze the worms into the tank for feeding the fish.
When to Start a New Culture?
Starting a new culture can be done any time after the culture establishes itself. Also, it would be more suitable to have extra cultures on hand for the possibility of culture crashes. On the other hand, sometimes there can be pest invasions in the grindal worm cultures. In that case, you may also need to start a new culture to increase the yield and remove the pests. For such cases, try to harvest as many grindal worms as you can and place them in a cup of water. While the grindal worms would sink to the bottom of the water, mites, flies, or eggs would float on the surface. Carefully flush the water with the pests and keep the worms from starting a new culture. To start a new culture simply follow the steps under the “Setting Up the Grindal Worm Culture” heading of this article.