Gardneri Killifish

Gardneri Killifish: A Complete Care Guide


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If you’re looking for a colorful fish ideal for a small to medium-sized tank, then the Gardneri Killifish (Fundulopanchax gardneri) could be perfect for you.

In this guide, we explain how to care for these beautiful little freshwater community fish and provide you with information on the best tank mates and environment to keep them in.


Gardneri Killifish is also commonly known as the Steel Blue Killifish or Blue Lyretail, and you often see them sold under that name in fish stores and online.

The fish’s name comes from the Dutch word “killy,” which roughly translates as a canal or ditch. As that name suggests, these little fish are generally found living in shallow water, including small streams, marshes, and water holes.

Killifish were discovered in 1911 in a river tributary in Nigeria by R. D. Gardner, and they are known to inhabit tannin-stained streams, ponds, and creeks in Nigeria and Cameroon. These amazing fish quickly gained popularity in the fish business due to their stunningly beautiful looks and small size. 

Availability And Price

Gardneri Killifish are not always readily available in your local fish store. Most fish are commercially raised on ornamental fish farms in Asia, and they don’t always find their way to all markets. However, you can generally buy the Steel Blue Killifish online.

As you might expect, the comparative rarity of these awesome fish does make them quite expensive. Generally, you can expect to buy an individual fish for around $15. Remember that you will have to pay for shipping if you buy your fish online.

For that reason, we recommend that hobbyists at the beginning of their fish-keeping journey might be better off keeping more inexpensive fish.

What Do Gardneri Killifish Look Like?

Blue Lyretails are beautiful fish to look at. 

These little community fish only grow to measure around 2.5 inches in length. But their brilliant coloration makes them truly eye-catching. The fish’s body is metallic green and blue with red spots randomly dotted over it.

Telling the two sexes apart is relatively easy, which is handy if you want to breed your Killifish at home. Female Gardneri Killifish are more of a golden-gray color with less bright decoration than the male. Also, female fish sometimes have a slight color variation with pink scales running down their lateral line and tend to be rounder than males.

How To Care For Gardneri Killifish

Caring for Gardneri Killifish is relatively hassle-free, although they do have a few specific needs that you must meet if the fish are to thrive. For that reason, we don’t recommend these fish for a complete beginner. Killifish are quite pricey to buy, so you don’t want to lose them because of a few rookie errors! 

Essentially, you want the tank to be set up correctly with suitable water parameters, decoration, and filtration so that the fish feel safe and secure. That, together with the correct diet, is the best way to ensure that the fish thrive and show their best colors.

Tank Size

Steel Blue Killifish are good small tank dwellers. That said, the ideal tank size for these fish should be at least 10 gallons.

In their wild environment, the bodies of water that the Killifish inhabit can sometimes dry up. To survive, the fish have evolved the ability to leap between water bodies like Betta fish. So, Killifish are agile fish, and you must be sure to choose a tank with a hood, lid, or cover slide to prevent any accidents and discourage your fish from jumping out.


Killifish need very clean water, so you need a good filtration system for your tank.

However, these fish generally inhabit shallow bodies of water where the flow is relatively slow. If the current in the aquarium is too strong, the fish will be tossed around and might struggle to swim. This may lead to the fish becoming stressed, compromising its immune system and rendering the fish more vulnerable to common fish diseases.

So, we recommend that you use a sponge filter or add a baffle to the outflow to buffer the flow rate without compromising the filter’s effectiveness. 

Tank Decoration

These fish are native to habitats with dense vegetation, so a Killifish tank should contain lots of live aquatic plants. 

You can also use twisted roots, driftwood, and rocks to create a natural aquascape. These fish can be a little shy, and a tank with plenty of hiding places will give the Killifish the safety and security they need to thrive. Also, male Killifish tend to be somewhat territorial and aggressive, so a tank containing lots of hardscape and planting can help mitigate that behavior and keep things peaceful.

Water Parameters

Gardneri Killifish are generally pretty hardy fish that can tolerate small fluctuations in water conditions in their natural habitat. However, in an aquarium setting, you want to keep the conditions as stable as possible. 

These fish prefer slightly acidic, softer water with a pH of 6.0 to 7.5 and a water hardness of 4 to 8 dKH. Check the water pH levels weekly with an aquarium water testing kit, and make any necessary adjustments.

Killifish are tropical species that need warm water temperatures between 65° and 75°F. Take care to monitor the water temperature daily by using an aquarium thermometer to flag any problems with your heater. 

Tank Maintenance

To maintain the Killifish tank in excellent condition, you’ll need to perform partial water changes of up to 20% every week. Every few weeks, rinse the filter media to get rid of sludge and replace the media periodically in line with the manufacturer’s recommendations.

Use an aquarium glass cleaner to remove algae from the viewing panes. When you carry out your partial water changes, use an aquarium vacuum cleaner to remove uneaten fish food, organic waste, and dead plant materials before they have a chance to decompose and pollute the water. Pay particular attention to areas around plant bases, under decorations, and beneath the filter unit where waste tends to collect. 

Finally, trim any overgrowth from all your plants, and remove dead or brown leaves.

What To Feed Gardneri Killifish

Gardneri Killifish are primarily carnivorous fish that feed mostly on insects and small crustaceans in the wild environment. The fish also feed on algae. However, in an aquarium, you can feed your Killifish regular meals of pellets, fish flake food, and frozen meaty protein, such as bloodworms and brine shrimp.

Feeding your fish a high-quality diet of premium quality fish foods helps them stay healthy and can also mean the fish display brighter colors.

You mustn’t overfeed your fish, as that can lead to health problems. So, feed your Killifish twice a day, offering only what the fish will clear up in a few minutes. It’s also worth removing any uneaten food so that it doesn’t rot in the tank.

What Are Good Steel Blue Killifish Tank Mates?

Steel Blue Killifish are typically peaceful aquarium fish that can live with other small peaceful fish species. 

On the contrary, some fish owners report that their Killifish are aggressive fin nippers, sometimes seen biting at the fins of their tank mates. Also, other brightly colored fish can be seen as competition by male Gardneri Killifish, which can trigger aggression in a community tank.

Some suitable tank mates for Gardneri Killifish include the following species:

  • Neon Tetras
  • Corydoras catfish
  • Danios
  • Rasboras
  • Clown loaches

Finally, you should not put too many male Killifish in your aquarium. Although these fish are not overtly territorial, they can show aggression if overcrowded. Also, female Killifish can sometimes be harassed, literally to death, if too many males are included in your collection.

As these are small tropical fish, they can be vulnerable to predation by larger, aggressive types of fish. So, be careful that you don’t include any species that might bully or even eat your Killifish.

How To Introduce Steel Blue Killifish To Your Tank

You must acclimate your fish properly before releasing them into the aquarium. If you simply tip the fish into your tank, you risk stressing them. Stress leads to a compromised immune system and possible disease outbreaks among the fish. So, you must always take the time to introduce any new fish to the tank properly.

We recommend that you always begin by putting your fish into a quarantine tank for at least ten days before moving them to your main display tank. That gives you a chance to observe the fish for any signs of disease and treat that before exposing your existing, healthy fish to the newcomers.

To acclimate your new fish:

  • Turn off the aquarium lights for the first three to four hours.
  • Do not offer the fish any food for 24 hours.
  • Use either the floating or drip method to acclimate the fish.

Once you’ve gone through that process, you can introduce the fish to the tank via a couple of acclimation methods.

The Floating Method

The floating method is the simplest way of acclimating your fish. All you need to do is put the fish in their bag on the surface of the quarantine tank. Allow the bag to float on the water surface so that the water temperature inside the bag gradually equalizes with the water temperature in the tank. 

After 15 minutes or so, make a small cut at the top of the bag. Add ¼ cup of tank water to the bag. Repeat that process every few minutes until the bag is full. Once the bag is full, you can add the fish to your tank.

The Drip Method

For the drip method, you’ll need to use a clean bucket and a small piece of aquarium airline tube.

Start by floating the bag in your fish tank for 15 minutes with the tank light turned off. Now, move the water and fish out of the bag and into the bucket. Take your piece of airline tubing and gradually drip water from the aquarium into your bucket. To regulate the drip rate, make a series of loose knots in the tubing.

Once the water in the bucket has doubled, take half the water out. Repeat the process. Once the water has doubled again, you can release your fish into their new home.

For the first couple of days, your fish might be rather timid and spend a lot of time hiding among the plants and the rocks in the tank. However, they should soon become braver and swim around the whole aquarium so that you can enjoy their bright colors.

Breeding Gardneri Killifish

It’s quite simple to breed Gardneri Killifish in your home aquarium. 

Ideally, you’ll need a 10-gallon breeding tank equipped with plenty of lush planting to provide cover for the fish. Excellent filtration is essential for breeding Killifish. To prevent the aquarium filter output from becoming too strong and so that the fry doesn’t get sucked into the filter intake pipe, we recommend that you use a filter sponge at both ends.

The tank temperature should be between 60° and 70°F to encourage the pair of Killifish to spawn. Also, you should feed your fish a protein-rich diet to bring them into prime condition for spawning.

Once the Killifish eggs have been laid, you need to remove all the other fish to prevent them from being eaten. You should see the new fish hatch within a few days. At first, you can feed the fry commercially prepared fry food and baby brine shrimp. When the young fish are large enough, you can also include bloodworms in the fry’s diet. Feed the fry brine shrimp three to four times every day to encourage healthy growth.

After a few weeks, you can transfer your new Killifish to the main tank.

Health And Disease

There are a few common fish diseases that can affect Gardneri Killifish, including:

  • White Spot Disease (Ich)
  • Velvet
  • Columnaris
  • Dropsy
  • Fin rot

That said, Killifish are generally pretty healthy creatures, provided that you offer them a high-quality, varied diet and keep their tank in pristine condition. 

In Summary

Gardneri Killifish are popular aquarium fish that can make a wonderful addition to an established community tank.

These brightly colored little fish can live in a small, 10-gallon tank with other peaceful species. Killifish are pretty easy to care for, although they do need pristine water to thrive, so we recommend that you have some experience in fishkeeping if you want to take on this species. If you fancy a fun project, you can try breeding the Steel Blue Killifish in a dedicated breeding tank.

Do you have Gardneri Killifish in your aquarium? Did you breed them successfully? Tell us in the comments box below.

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