How to grow Mosquito Larvae for your fish


What are mosquito larvae?

Mosquitoes have 4 stages in their life cycle. The mosquitoes we see flying around are the 4th and last stage. The larvae are the 2nd stage of the life cycle. To get a better understanding, let’s look at all the stages in brief.

Stage 1 (Eggs)

When female mosquitoes find stagnant water that is suitable to lay eggs in, the eggs are laid in clusters. These clusters, also called rafts, float on top of the water. They hatch anywhere between a few days to several months after being laid, depending on the water temperature.If you end up with too many eggs, you could feed the eggs directly to the fish as well. Doing so will stop them from hatching and turning into adults, so there will be fewer mosquitoes around to bite us.

Stage 2 (Larvae)

This is the stage of most interest to us, as fish keepers. When the baby mosquitoes hatch from the eggs, they are called larvae. They wiggle around with jerky motions in the water, and are also called wigglers for this reason. The larvae feed on algae and other micro-organisms that are found in the water. They turn into pupae in 5-7 days. Fish love to eat them.

Stage 3 (Pupae)

The next stage in a mosquito’s life cycle is called a pupa, or a tumbler. The larvae turn into pupae and spend the rest of this stage just under the water surface. They look like tiny commas. While they remain mostly inactive, they can still dive deeper when disturbed. Pupae turn into adults in about 2-3 days. If there are too many pupae floating about, you can feed them to your fish as well, to stop them from growing any further.

Stage 4 (Adults)

The adults emerge from the pupae, fully formed into adults. These are the ones that fly around, biting and irritating us. Then they lay eggs, and the cycle continues.

Why you should raise mosquito larvae

Free live food

Raising mosquito larvae is very easy and doesn’t require a lot of time. All you need to do is set up conditions that mosquitoes lay eggs in. Then you just wait a few days, and mosquitoes will come and lay their eggs. So you get mosquito larvae virtually for free! You don’t even need to feed them anything. They eat micro-organisms in the water.

Enhance fish colours

Feeding aquarium fish live food puts the fish in a good mood. Live food also makes their colours more vibrant, making them more striking to look at. Wouldn’t you want your fish to look brighter and more colourful than others of the same species? Fish just love to eat mosquito larvae. Worm-like creatures that wiggle in the water are irresistible to fish, even the ones you won’t think are predators!

Fish get to hunt

Several species of aquarium fish are natural predators. When given live mosquito larvae that wiggle about in the water, these fish will hunt them down and eat them. This gives them a chance to exhibit their natural behaviour, which is very interesting to watch. Some fish just chase after the larvae, while others are ambush predators. They wait till the larvae come close to their mouth, then attack them suddenly. Predatory fish can become very bored if not given a chance to behave naturally. They might even become aggressive.

Induce breeding

If you are trying to breed fish, mosquito larvae can be very useful. Many species of fish require a special setup to get them to breed. You could isolate a potential breeding pair in their own tank, keep suitable decorations for them to lay eggs on, and keep the temperature in a range which can induce breeding. But the fish will still need to be fed live food before they actually start breeding.

How to raise mosquito larvae

Equipment you will need

You will need a bucket, barrel or tub, and a small fish net to catch the larvae in. The bigger the container, the more larvae you can harvest.

Location

The container should be placed outside in a shaded area, where the water won’t become too hot. If placed in a sunny area, the water will become too hot and the larvae will die. A couple of hours’ sunlight should be ok, if it is not too intense. The container should be place at a distance away from your home, otherwise the mosquitoes that come there to lay eggs will also enter you home.

Climate and other factors

The mosquito larvae do well in temperatures ranging from 64.5 to 93 °F (18 to 34 °C). At temperatures below 50 °F (10 °C), the eggs will become dormant and will hatch only when the temperatures rise again, even if it takes several months.

Making the water ready

The water needs to be dechlorinated, because chlorine in the water will kill the micro-organisms that are the larvae’s food source. You could use rainwater or water that you know is chlorine-free. You could also use a dechlorinator that can be bought online or at any local fish store. Or, you could simply leave the water as it is. The chlorine will leave the water in 24 hours.

Now, mosquitoes are attracted to the greenish-brown water in which algae has started growing. During warmer months, you could just leave the container with the water for a couple of weeks. Algae should start forming on its own.

However, if you want to speed up the process, you can do the following. Take a filter media bag, and fill it with grass clippings or vegetable scraps from the kitchen. You could also add some dirty water from your aquarium. The algae should appear a lot faster using this method, as you have put in the necessary nutrients in the water, essentially fertilising the water.

Giving it some time

Now that the setup is complete, all you have to do is wait. If the temperature is suitable, the larvae should appear in a week or two. You will need to keep checking every day, as the larvae can turn into pupae in as little as 5 days.

Harvesting the mosquito larvae

Once you are able to see the larvae swimming about, you can grab your aquarium net to scoop them out. However, the smaller larvae will fall out from between the holes, as the holes of most fish nets are too large for them. You will need a net that has very small holes and is designed to catch baby Brine Shrimp or Daphnia.

Once you get close to the container, the larvae will likely go deeper into the water. But they need to breathe air directly from the atmosphere. So they should be back up in a couple of minutes. You will need to stay still with your net ready to scoop as many as you can in one go.

Creating a non-stop supply of fresh mosquito larvae

If you scoop up all the larvae, it could take up to a week for more eggs to be laid and more larvae to hatch. If you want a continuous supply of larvae, you will need to keep two containers, both with loosely fitting lids. When you set both the containers up, cover the 2nd one with the lid once you start noticing larvae in the 1st container, cover it with the lid and uncover the 2nd container. That way, by the time you use up the larvae from the 1st container, the 2nd one will have larvae in it. However, the climate needs to be in optimal conditions for this to work.

Syed Baseeruddin Hyder

I’ve been keeping fish and invertebrates in aquariums for over 5 years. Over the years, I’ve kept more than 15 different species of fish and invertebrates. Through ParadiseInATank.com, I hope to guide new and experienced fish keepers alike with as detailed information as I can get.

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