How Big Do Killifish Get?

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Written By Fun Fish Tanks

I Love my Fishes 

The Killifish is not a fish that you will find in every aquarium. This comes off as peculiar because they are beautiful fishes and do not demand too much care.

So this brings curiosity to one’s mind to know more about this gorgeous species. There are multitudes of species of this fish. You can find over 1250 species of this fish.

With this many species in existence, it makes this fish very interesting. Questions can pop up in your head such as how big they get, what is their lifespan, and many more.

So in this article, we will look into how big do killifish get and what are the factors that affect their size.

How big do Killifish Get On Average? 

As mentioned before, there are over 1250 species of Killifish. It is a given that all of the species are not of the same size. Some grow to be big and some don’t become big.

So the size of the Killifish depends on the species. Different species can retain different sizes as they grow. Some species are small such as 1 or 2 inches, and some can reach about 6 inches.

Some species can even grow up to 18 inches. Therefore the average size of the Killifish is 6 inches.

The killifish species which are the biggest is the Gulf Killifish. Whereas the smallest Killifish is Least Killifish or Heterandria Formosa. 

How Long Does It Take a Killifish to Reach Full Size?

Killifish are fast growers. In an aquarium with perfect tank condition, they grow quickly and reach their maximum size. The maximum size depends upon the species of Killifish that you have. Although, the growth rate of Killifish is slower in captivity than in the wild.

Do Killifish grow bigger in aquarium than wild?

Similar to most fish species, Killifish tend to attain a greater size in the wild than in an aquarium. These species of fish will not be able to grow to their true size. It is mainly because of the variation in the habitat of the two. In an aquarium, the Killifish will grow up to 6 inches, but in the wild, they can grow up to 18 inches.

What effects the growth of Killifish in an Aquarium? 

Killifish, as you already know are fast growers. Although in an aquarium several conditions affect the growth of Killifish. The aquarium’s size, water conditions, water parameters, diet, and tankmates all come into play in the growth of Killifish.

What are the tank conditions for the Killifish to grow properly? 

As you are already aware, in an aquarium, several factors affect the growth of Killifish. You must have the tank conditions and parameters towards the liking of the Killifish so they grow effectively. 

  • Tank Size for Killifish: The average tank size for a pair of Killifish is 20 gallons. Before adding Killifish to your tank research the kind of species you want. If they are of the smaller-sized species, you can keep them in a tank of 10 to 15 gallons. If you wish to add more Killifish then you have to increase the size of the tank as well according to the need of the species you want to keep.
  • Water parameters for Killifish: As there are several species of Killifish, the water parameter preferences change with each species. The average water temperature for Killifish ranges from 68℉ to 72℉. When it comes to pH levels, the average levels are 6.0 to 7.0. The hardness of the water must be from 120 to 160 ppm. These are just the average ranges of water parameters for Killifish. 

Try to keep all these water parameters stable at all times. If they fluctuate then it can harm your fish and hinder the growth of Killifish. Keeping the water parameters to the required levels at all times will enhance the growth of the fish.

  • Choosing best tankmates for Killifish: Killifish are peaceful fishes. You can keep a sole Killifish in a tank, and you can keep them in a community tank as well. They are not the type of fish that shoal, meaning they don’t live in groups. When keeping them with other species, make sure they share a peaceful temperament. Neon Tetras are a good species to keep Killifish with. 

If the case of keeping Killifish with their kind, don’t keep two males together in a tank. A male Killifish will become aggressive in the presence of another male. You can keep females together in a tank, females can live together peacefully.

  • Give them a proper diet: The diet of Killifish is characterized by live food. Killifish are carnivores, and they enjoy live food. You will have to feed them live shrimps and worms. They don’t do well if they are given frozen food. With the diet of live food, the Killifish will be able to grow without any trouble. So feed them live food and watch them grow.
  • Filtration and lighting: For the Killifish to grow, you will have to maintain the water condition and always keep it clean. For this, a good filtration system is required. The Killifish create a lot of waste compared to other fish species. So for this waste to go away, strong filtration is a must. A hang-on-back filter is the best one for a tank with Killifish. If you want to go for sponge filters, make sure you opt for a high-quality one. 

The lighting of the tank plays a major role in the growth of Killifish. Almost all the species of Killifish prefer moderate lighting. 

For the ideal growth of your Killifish, you must keep the water conditions stable. Killifish don’t fancy fluctuations of water parameters. If you feel like your Killifish is not growing properly, check the water parameters and their diet. Set the parameters straight and provide them with live foods. They won’t face any problems regarding growth.

Now, as we come to the end, we can say that the size of the Killifish depends upon its species. There is a multitude of species of Killifish, and each species grow to a specific size. In an aquarium, they cannot their maximum size, as in the wild. There are also several factors that you have to look upon regarding the growth of Killifish. They are diet, tank size, tank mates, water parameters, etc. You must keep everything at the preferred levels for your Killifish to grow properly.

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