Chinese Algae Eater Care Guide

Are Chinese Algae Eater Fish Aggressive?

Chinese Algae Eater Care Guide7 mins read

Fact checked by
Tal Halperin
Reading Time: 10 minutes
Chinese algae eater care guide
Image from Flickr

If you love the idea of including an algae-eating fish to keep your tank clean, the chinese algae eater is a great lesser-known alternative. Especially if you want something other than the more common Pleco family or Cory Catfish, you may consider these smart and dynamic fish.

However, after reading about their reputation, many fish keepers find themselves asking ‘is the chinese algae eater aggressive?’ You may worry also about chinese algae eater size and how it will get on in a community tank.

Many myths about these fish can put aquarists off buying them. However, when you are informed, you will find it is easy to take care of them, so read on to find out how.

Breed Overview

OriginSoutheast Asia
LifespanUp to 15 years (if well cared for)
SizeUp to 12 inches or 30 cm
ColorsMottled greenish brown
Water TypeFreshwater
Tank SizeMinimum 55 gallons
TemperamentSolitary and curious, but can be aggressive in wrong conditions
Water Temperature24-28 C 74-82 F
Water pHNeutral
FoodOmnivores (despite what their name will suggest)


The Chinese Algae Eater may not be brightly colored, but it is a remarkable fish that is perfectly camouflaged. In fact, if you keep it in the right environment, you will see how expertly these fish blend into their surroundings.

1. Body Shape And Color

Unlike some Algae Eaters, they have a relatively slender body. One major characteristic they do share, however, with other Algae Eaters is a slightly rounded head. This is due to the placement and formation of their sucker mouth.

Color-wise, they are often a light mottled greenish brown. This comes with bands of dark brown ranging to black or brownish grey on their bodies. In general, this coloring helps camouflage them in their natural habitats.

  • Chinese Algae Eater Size- One of the biggest mistakes people make when looking after this fish is not realizing that it can grow up to 12 inches or 30 cm! As a result, even if your tank is technically large enough, it may be that your fish gets so big it threatens tank mates. In fact, chinese algae eater size is one main reason why territorial disputes break out.

2. Color Morphs

Like with many aquarium fish, a variety of color morphs are available. The most common alternative is gold, but be very careful. Often when you see these fish, they have more likely than not been injected with dye.

This causes health problems in the fish and is not something for those who care about their fish’s wellbeing. So, steer clear of these fish.

Other morphs, such as the albino and leucistic morphs, come from simple genetic mutations. These do not result in fish that are in pain. Plus, pain and stress can result in the chinese algae eater aggressive tendencies many hear about.

Author’s Note: It is very difficult to tell the males from the females in this species. This is another reason why they are considered relatively challenging, as if you want to breed them (more on this later) this may become an obstacle.

Generally, if you have a slightly plumper fish, it will tend to be female.

Tank Setup And Maintenance

Tank setup and maintenance for chinese algae eater
Ideally, tank water should be changed by about a third once per week.

Tank setup and maintenance for a chinese algae eater generally depends on other fish in your tank. Most people don’t want to keep chinese algae eater by themselves. Thus it’s more likely you will be introducing them to a community tank.

General Requirements

In the wild, these fish live in fast-flowing streams that have very clear water. As a result, it’s important to ensure water is kept squeaky clean. You can do this with the aid of a filter that filters at least 4x the tank capacity per hour, depending on other tankmates.

A HOB (hang on back) or sponge filter can work. Depending on whether other species are strong swimmers, you can also use a canister filter to ensure this cleanliness. Remember, chinese algae eater size means they do produce more waste than other bottom feeders.

Author’s Note: Ideally, tank water should be changed by about a third once per week. You can do this with a specialist aquarium vacuum, just be careful to avoid your fish while you are hoovering along the bottom. This also helps get rid of any detritus your fish hasn’t eaten.

Creating A Suitable Habitat

One characteristic of this fish that is similar to other Algae Eaters is that they like to hide away! This often happens when they feel threatened. Therefore, creating places within your tank where they can do this is very important.

You can do this by positioning rocks so that they form crevasses, or by buying tunnels for your fish to hide in. Some of these are available in the decoration section of any good aquatics store.

However, some aquarists put a piece of PVC piping in the tank for these fish. This is popular for many bottom-dwelling, shy Algae Eaters, to retreat into. Although it doesn’t always look very nice, your fish can love you for it. And, you can easily disguise or camouflage it with plants. Just remember to account for your chinese algae eater size by making it large enough to accommodate their full adult length and width.

Don’t ever use sharp gravel on the bottom of a tank with a chinese algae eater in it! You will find that this kind of gravel hurts the delicate stomachs of these fish.


Despite their reputation, the chinese algae eater can work with a variety of tankmates. However, this is only if there is enough space and they are fed correctly. For an easier Algae Eater, you may prefer the Pleco Fish, which also gets on with similar species. However, good tankmates that account for the chinese algae eater aggressive tendencies are as follows:

  • Discus Fish
  • Angelfish
  • Mollies
  • Guppies
  • Swordtails
  • Platies
  • Betta Fish
  • Small Amazonian Cichlids

Tankmates to avoid include anything that will share territory on the bottom of the tank. This includes species such as Cory Catfish, Kuhli Loaches, and forms of Gobies and Pleco fish.

These fish can be targeted by the chinese algae eater if they don’t get enough protein. This can happen when the Algae Eater tries to suck the slime coating of other fish. It can be serious, considering chinese algae eater size and sucking strength. So, to prevent this, see the behavior section.


Feeding to chinese algae eater
At a young age, your fish will easily be able to get the required nutrients from algae wafers. Image from Flickr

The name of this fish can be very misleading! Besides the fact they do not come from China, they actually require much more than algae to stay healthy.

At a young age, your fish will easily be able to get the required nutrients from algae wafers. However, as it grows older, the larger chinese algae eater size means it will need fresh and or frozen protein like daphnia or bloodworms to balance its diet.

The chinese algae eater will not often venture away from the bottom of the tank. As a result, it’s important to feed food where you can ensure that at least some of it sinks to the bottom. Otherwise, despite their larger size, other fish can outcompete them.

Behavior And Temperament

The chinese algae eater is a peaceful fish. However, if its needs are not met, it can actually become dangerous to other fish. No fish is aggressive inherently. However, chinese algae eater aggressive behaviour results from these unmet needs as the fish tries to meet them in other ways. It needs protein as it grows and develops, and if it does not receive this, it can become predatory to other fish. However, with its sucker mouth, it can only do so much damage.

What exactly happens? If not fed sufficient protein, the chinese algae eater will latch onto the slime coating of other fish. Then, it will suck to get the necessary nutrients. If a chinese algae eater destroys this, your other fish become more susceptible to infection. Plus, it can be painful in itself.

Also bear in mind it is not a social, schooling, or schooling fish. It can in fact become aggressive to those of its own species.

Apart from this, you may see these guys happily sitting on the bottom of the tank or on the sides of the tank walls. You will even see them hiding on driftwood and bits of rocks. When it comes to habitat, they do like to move around.

However, they are generally shy, so you are more likely to see them tucked away somewhere. Despite their reputation, they have tons of character and are very interactive.

Is The Chinese Algae Eater Aggressive To Its Own Species?

Is the chinese algae eater aggressive to its own species?
Chinese Algae Eaters can not get along with their own species unless you have a very, very large tank (over 100 gallons/455 liters at least). Image from Flickr

Like the Betta Fish, the chinese algae eater can not get along with their own species. Unlike the Betta Fish, this CAN work in a very, very large tank (over 100 gallons/455 liters at least). Truthfully though, it is not ideal unless you have lots of experience. This is partly due to territorial issues because of the size that these fish grow. If you do this, you need to be able to handle chinese algae eater aggressive behaviour if it does break out.

So, long story short, they can be semi-aggressive towards their own species in general. Fish aggression in general, and chinese algae eater aggressive tendencies included, are complex topics. Often, fish just have unmet needs.

However, it’s important to understand these needs may include a preference against sharing territory with certain other fish. As you adjust your expectations, you will find no fish – the Chinese Algae Eater included – is inherently aggressive.

Pests And Diseases

Chinese Algae Eaters are sensitive fish, and they require very clear water conditions. Apart from this, however, they are prone to many of the same diseases as other freshwater species.

Bacterial Infections

Bacterial infections result from poor water quality, and the chinese algae eater can be more prone to them than most due to the crystal clear conditions they live in in the wild. Thus, they are very sensitive to dirty water.

If you see your water become cloudy, it’s a sure sign you need to change it more frequently or invest in a stronger filter. However, including plants can also help filter nitrates and other toxins.

If you see dark patches or ragged, sore patches appear on your chinese algae eater fish, especially around the fins or mouth, take note. This is a sign of a bacterial infection such as fin rot. You can treat this by isolating the fish and offering an over-the-counter antibacterial medication from your local aquatics store.

Fungal Infections

One common risk with any algae-eating fish is the infection of your fish’s sucking mouth. Be very careful if you see any white growths surrounding your fish’s mouth. A fungal infection can be painful, prevent your fish from feeding, and can spread to other parts of its body. In extreme cases, it can even cause haemorrhaging.

To treat this, it’s good to remove the fish to a separate tank and treat it with a saltwater bath. Do this until the fungal infection goes away.

Parasitic Infections

Parasitic infections such as Hexamita or hole-in-head disease also result from unclean water but manifest differently. Parasites can weaken your fish’s immune system and make them more susceptible to other infections. If they are in pain, this can also be another cause of chinese algae eater aggressive behaviour to other fish.

As they are not bacterial, you cannot treat them with antibiotics. Instead, a saltwater bath is the best option. Other parasitic infections include ich, and velvet, or ‘gold dust’ disease.

What To Do If Another Fish Gets Attacked By A Chinese Algae Eater

What to do if another fish gets attacked by a chinese algae eater
If possible, it’s also a good idea to isolate the Chinese Algae Eater in case they do this to other fish. Image from Flickr

If your chinese algae eater attacks another fish to suck the slime coating you may worry that your other fish can get infected. Although it comes from stress, chinese algae eater aggressive behavior is no joke!

This behavior generally happens to slow-moving fish that hang in one place in the water such as discus fish. It is especially important to prevent because the mouth of the Chinese Algae Eater is lined with small hooks that can do a lot of damage.

If it happens, it’s best to be on the safe side and transfer the injured fish to another tank. You should then use a saltwater bath to prevent the growth of the disease.

If possible, it’s also a good idea to isolate the chinese algae eater in case they do this to other fish. This kind of behavior is a sign your chinese algae eater doesn’t have its dietary needs met. Or, it may be your chinese algae eater size has increased to the point it is feeling territorial.

Author’s Note: If you don’t have enough space, you may find you have to decide between isolating the Algae Eater, or the injured fish. In this instance, it’s best to factor in the severity of the injury, and how aggressive your Algae Eater seems. Try feeding more protein for a few days to determine how easily you can fix this behavior.


In keeping with their mixed reputation in terms of behavior, science doesn’t know much about the breeding habits of these fish.

There are anecdotal reports of them spawning in mixed community tanks. This is especially when fishkeepers don’t pay that much attention. However, it’s very hard to get them to breed deliberately. One of the biggest challenges is the difficulty in sexing them, and the aggression towards their own kind.

However, some of these fish are bred commercially on fish farms. They are in fact a delicacy in some of the countries where they come from. This naturally relies on breeding, but in general, it involves the addition of hormones. Therefore it’s not very viable for the home fishkeeper.

Final Thoughts

Chinese Algae Eaters
Chinese Algae Eaters have gained a reputation for being difficult, and this is sometimes not without reason. Image from Flickr

The chinese algae eater gained a reputation for being difficult, and this is sometimes not without reason. But generally, this stems from owners not understanding their needs correctly.

Are you prepared for a slightly more challenging fish and are willing to put in the effort to learn about their unique requirements? The chinese algae eater aggressive behaviour has a fiendish reputation but in competent hands, it should not be a problem. In fact, overall, the chinese algae eater can make an unusual and rewarding tankmate that brings a back-to-nature look to your aquarium.

Frequently Asked Questions

Are Chinese Algae Eater Fish Aggressive?
Misconceptions about the aggression of the Chinese Algae Eater have generally arisen because of how they need a lot of space. Like with any fish, aggression can arise when there is not enough territory. However, the reason why this may happen more frequently with this species is their unassuming appearance which leads some beginners unaware of how big they grow, but also of how their dietary needs change over time.
Are Chinese Algae Eaters fish tropical fish?
Yes, Chinese Algae Eaters are tropical. This may be surprising and cause some confusion due to their name, as some coldwater fish like Goldfish and White Cloud Mountain minnows also originated in China. However, the Chinese Algae Eater actually comes from the warmer climate of southeast Asia where it lives in clear, fresh rivers and streams. Another confusing name for it is the Indian Algae Eater. However, you may also hear them named sucking loaches.
Are Chinese Algae Eaters omnivores?
Yes, contrary to what their name may suggest these fish are omnivores, and in fact they become more dependent on protein as they grow older, which is a leading cause of their aggression sometimes if these needs are not met.
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Sydney Perry

Sydney Perry has loved fish since she was a child and has enjoyed keeping many varieties over the years, ranging from black moors and shubunkins to betta fish. As a lover of nature and of Japanese culture, her dream tank is an Iwagumi aquascape, combining fish with carefully crafted aquatic landscapes in miniature.