Butterfly fish are in some ways the very epitome of the saltwater aquarium hobby! These fish tend to be more difficult to care for. But you are rewarded with beautiful colors, large size, and an active disposition that is hard to match! Unfortunately, their personality means that you can’t usually keep more than one. But sometimes, one can be more than enough!
Understanding the Butterfly Fish Family
Butterfly fish are what we call live rock grazers. There are a few fish in this category, including angelfish, tangs, surgeonfish, damselfish, and Mandarin Gobies. They look superficially similar to saltwater angelfish but they don’t have the cheek spine along the gill cover.
But they are just as strongly flattened laterally and many have extended jaws that allow them to pluck small prey out from between rock crevices.
Many butterfly fish also have false eye spots on their rear fins, typically the dorsal fin. Eye spots and fin extensions can act as social cues for related fish to recognize each other. However they are also distractions for potential predators.
The large “eye” peeking out from a coral crevice can fool a predator into thinking a butterfly fish is larger than it is. And since predators almost always try to aim for the head of their prey, a hit to the fins is much easier to recover from than getting grabbed by the face!
Since butterfly fish are a large family of fish it can be hard to truly characterize them. They range in size from 5 to over 12 inches but most grow to be 7 to 9 inches long. This makes them only really keepable in aquariums larger than 100 gallons.
Some are very sensitive to even minor issues in poor water quality while others are very hardy. Some refuse to eat anything but coral polyps and sponges while others are adaptable and eat anything you offer them! There is a lot to learn about butterfly fish care so let’s dive in together!
- Scientific Name: family Chaetodontidae
- Origin: Tropical coral reefs worldwide
- Length: 5 to 12 inches
- Aquarium Size: 55+ gallons
- Ease of Care: Easy to DIfficult
Types of Butterfly Fish
There are actually dozens of different types of butterfly fish that can be found in the wild and the aquarium trade. But here are the four species you are most likely to encounter at your local pet store!
One of the most beginner friendly types of butterfly fish is the Auriga Butterfly Fish (Chaetodon auriga)! Also known as the Threadfin Butterfly Fish, it is a species that is hardy enough even for beginning saltwater aquarists to try. They are fairly large fish when fully grown though, with 8 inches being typical and 10 to 12 inches reported in the wild. However they are one of the most flexible species when it comes to adjusting to the meaty frozen food and pellet diet offered in captivity!
Racoon Butterfly Fish
The Racoon Butterfly Fish (Chaetodon fasciatus) is another beautiful beginner-friendly species that adapts well to captivity. They can be a little more aggressive towards their tank mates; especially other Butterfly Fish.
However you can sometimes get away with adding a small group of them to an aquarium at the same time. That way, no one fish will get bullied by aggressive established residents. You will need at least a 125 gallon aquarium if you are looking to keep one of these active, hardy fish healthy.
Saddleback Butterfly Fish
Saddleback Butterflyfish (Chaetodon ephippium) get their name from the obvious black wedge along their backs that looks just like the saddle on a riding horse! A slightly larger type of butterfly fish, they average 10 inches long in captivity and can exceed a foot in nature.
Keeping Saddleback Butterfly Fish with other tank mates can be a little challenging due to their semi-aggressive nature. While they are stressed by overly dominant tank mates they tend to pick at peaceful fish. It’s best if the Saddleback Butterfly Fish is the most dominant fish in the tank and it has tank mates that are fast enough to escape the occasional chase.
Copperband Butterfly Fish
Of all the types of butterfly fish the Copperband Butterfly Fish (Chelmon rostratus) is probably the most immediately recognizable! Bright silver and copper alternating bands along the flanks are distinctive enough. But the long, beak-like snout is even more fascinating, giving them the alternate common name Forceps Fish!
Unfortunately, Copperband Butterfly Fish are very difficult to keep in captivity. They are sensitive to even low levels of ammonia. And they are harder to wean off of eating coral polyps, sea anemones, and other desirable invertebrates. These fish are best left to saltwater butterfly fish experts!
Are there Freshwater Butterfly Fish?
There are no freshwater butterfly fish; at least no fish from this family living in rivers and lakes. All of them are found only in tropical seas and coral reefs. But believe it or not there are a few freshwater fish that sometimes get mixed up when trying to learn about butterfly fish! The name is so popular that it is widely attributed to a few entirely unrelated fish.
What about African Butterfly Fish?
The most popular of these “freshwater butterfly fish” is the African Butterfly Fish (Pantodon buchholzi). And as you can see from its drab colors, strange fins, and cigar-shaped body, it has very little to do with marine butterfly fish. In fact, it is closely related to Arowanas, only it grows no larger than 4 to 6 inches.
It seems that they are nowhere near as beautiful as a butterfly insect, let alone a saltwater butterfly fish. So why do they have this name? They get their name from their broad fins; African Butterfly Fish can glide!
In fact, most arowanas and their relatives are excellent jumpers and will leap several feet to escape predators and catch prey flying by or climbing on tree branches. The light weight of the smaller African Butterfly Fish makes it easier for the fish to gain a little extra lift when leaping!
Butterfly Betta Fish and Butterfly Koi Fish
Similarly, there are koi and betta fish that share the title “butterfly fish!” The Butterfly Betta is a popular common name for the Delta Tail Betta Fish. Butterfly Betta Fish have a tail fin that’s shaped like a crescent fan rather than the wide, flowing skirt of a common long-finned betta. They also tend to have distinctive color patterns; two toned Butterfly Bettas are often of show quality!
Butterfly Koi Fish, on the other hand, are any long finned breed of koi. Also known as Dragon Koi or Hirenagagoi in Japanese, they are also often very slim. Visibly slimmer than standard koi but their wafting fins give them an ethereal quality that makes them popular in ponds. Butterfly Koi are a variety meant for top-down viewing, as in an outdoor koi pond!
Ultimately, there are no freshwater butterfly fish; only the marine fish in the family Butterflyfish!
Caring for Sea Butterfly Fish
Butterfly fish are not too demanding once you get past their odd eating habits. Many do require very clean water conditions as well. But once they are settled in they are long lived and hardy aquarium residents!
Butterfly Fish Aquarium Size
Since butterfly fish are on the larger end of the spectrum, you will need a more spacious than average fish tank to care for them. Most butterfly fish will grow around 8 inches or more in length. This means that an aquarium should be 100 gallons or larger when keeping them in a community tank.
Smaller species can be kept in aquariums of up to 75 gallons in size. Just keep in mind that these fish are extremely active. And if you intend on having your butterfly fish supplement their food with natural grazing then they will need a lot of aquarium space to ensure they don’t pick your live rock clean!
Butterfly Fish Tank Mates
Choosing tank mates for butterfly fish can be a little challenging because their temperaments vary so widely. Some, such as the Copperband Butterfly Fish are very peaceful and keep to themselves, busily hunting for coral polyps and worms.
Others, such as the Racoon Butterflyfish are more likely to bother their tank mates. Especially other fish that graze on live rock. And all butterfly fish tend to be very intolerant of each other. Even Copperband Butterfly Fish will fight with one another.
Just be certain that you don’t choose an especially aggressive member of these normally peaceful to semi-aggressive families. For example, the Maroon Clownfish (Premnas biaculeatus) can be a handful for its tank mates even in a spacious aquarium!
Their small mouths and grazing feeding habit means you can even keep marine butterflyfish even with much smaller fish like Fire Gobies.
Are Butterfly Fish Reef Safe?
Unfortunately, most butterfly fish are some of the worst fish you could ever add to a reef tank. They are specialist coral and sponge feeders and would devastate any reef aquarium by picking the skeletons clean of flesh. Many butterfly fish will also gladly feed on Feather Duster Worms and other sessile organisms.
On the plus side, they also eat majano and aiptasia sea anemones with relish, especially Copperband Butterfly Fish. Normally these tiny cnidarians are almost impossible to get rid of. But owning a butterfly fish is one way to actually eliminate them in a fish tank!
Feeding Butterfly Fish
Feeding butterfly fish is one of the main challenges to keeping these animals alive over the long term. The issues you run into are similar to those of their close cousins the Marine Angelfish. Butterfly fish are coral and live rock grazers. They eat the slow growing, encrusting marine life that is constantly growing in the sea.
Algae, sponges, soft corals, hard corals, feather duster worms, and other non-moving prey are what they feed on. It is nearly impossible to provide them with the quantity and variety they need because these all grow very slowly.
In nature a butterfly fish can simply swim over to a new patch of rock if the current spot is all out of encrusting organisms. But in a fish tank it can’t do that.
This is also one reason why butterfly fish, as well as angelfish, tangs, and other rock grazing fish, tend to be so aggressive towards each other. Since the food runs out so easily and takes so long to grow back, it pays to ensure other fish aren’t stealing from your garden. Many of these fish will even recognize and chase away other grazers besides their own kind.
Your best option is to only buy a butterfly fish that has already been weaned onto frozen and prepared food. Ask your local pet store to feed your butterfly fish in front of you – or come back during a scheduled feeding to watch.
Part of the quarantine process for professional marine pet stores and manufacturers is often to get picky fish eating standard prepared food. This way a new fish does not simply starve a few days after you get it home, making you less likely to shop there again in the future.
Fresh, meaty foods are the best way to entice a picky eater to end their hunger strike. This includes brine shrimp, tubifex worms, and copepods.
Since many of these less coral-specific feeders are truly omnivorous you will want to balance this with nutritious macroalgae. Macroalgae can be purchased fresh, dried, or even grown in your very own refugium!
Frequently Asked Questions about Butterfly Fish
Butterfly fish are actually a very large grouping of marine fish. Some are on the easy side to care for, especially the commonly available types I listed earlier. But some are much more challenging to keep. Be certain of the species you are looking at before making an impulse purchase!
Butterfly koi are actually a breed of freshwater koi carp! They get their name from their long, flowing fins like those of a butterfly. But they have little to do with the saltwater butterfly fish.
Butterfly betta fish are also a freshwater fish. Their fins are even longer than those of the standard long finned betta fish, with a nicely rounded form.
could be considered reef safe: with caution. But there is always the chance that they will decide to pick at one and have a taste.