Angelfish and Algae eaters

In this post, we will understand the relationship between Angelfish and some Algae eaters. We will also discuss the algae eaters general biology and tank requirements.  

Angelfish and Algae eaters

Sometimes algae levels in a freshwater aquarium need control in addition to chemical moderators. There are specific fish that can control the algae population in the aquarium. Few of these fish can be set up with Angelfish such as otto and molly fish.

Algae eaters

Algae can appear in all types of aquarium, whether it is a planted, marine, community or even Cichlid aquarium. In a balanced aquarium, these can be controlled by algae consuming fish or by manual removal during aquarium maintenance.

Some algae indicate the poor quality of the water. But not all algae in the aquarium are bad, a small amount is unavoidable where there are water, light, and nutrients. Control or prevention is the key to controlling them and often algae-eating fish can be important allies in combating them.

It is very common the appearance of algae in newly built aquariums and constant instability of the water parameters. During this period, it is recommended to introduce fast-growing plants to consume excess nutrients and compete with the dreaded algae. Only after the aquarium is in equilibrium, insert the first algae eaters, or other fish.

Otocinclus catfish algae eaters

Otocinclus catfish are extremely amicable and pacific fish, they are great for community tanks. They are schooling fish and usually feel more secure and comfortable in groups of at least 6 individuals. 

They are long, thin fish, covered with 23 to 24 bone plates that overlap to replace the scales. The head is relatively flat and ends with a mouth with a sucker shape. Their belly is white or slightly yellow. They have a longitudinal black band from the mouth to the caudal peduncle. Hard rays are present in the pectoral and dorsal fins, which serve as a defence against predators.

They are oviparous. The females release sticky eggs on a flat surface that will then be fertilized by the males. Eggs hatch within two days, the fry remain attached to the yolk sack, feeding on it. They will be swimming after about two or three days. There is no parental care.

They are very popular in the aquarium hobby and are often mistakenly sold as janitor fish that feed on food scraps or faeces from other fish. Although they can feed on fish food at the substrate, their primary diet consists of scraping algae off the glass, plants, or any other ornament in the aquarium.

They have a shy nature and feed most of the time. Thus, may not compete with other fish for food. For this reason, their mortality rate in the first few weeks can be high when introduced into a new aquarium. 

Observe carefully before purchasing them, if they have a very sucked belly, avoid buying them. If they are in this condition and you still want to buy them, try to isolate them in a quarantine aquarium for a few days and provide a specific feeding scheme for bottom fish and alternative foods, until they are more full-bodied and able to go to the main aquarium. 

If you are unable to isolate them in another aquarium, provide background food freely after about an hour after the lights are turned off, this way they will feed without competing with other fish.

How do Ottos behave?

They should preferably be kept in a densely planted aquarium, as they spend most of their time “resting” or feeding on algae over leaves, glass, and other objects in the aquarium.

They present extremely peaceful behaviour, ignoring other fish in the aquarium. They should be kept in groups of at least six individuals so that they feel more secure and show their natural behaviour. 

What do Ottos eat?

Ottos are essentially herbivorous. They feed on soft algae, mainly diatoms. In an aquarium, it is recommended to vary their diet with peeled vegetables such as zucchini, carrots, potatoes and cucumbers, as well as specific rations for bottom fish.

Molly algae eaters

Molly fish are extremely peaceful by nature, they also make awesome inhabitants for community tanks. They are not demanding fish and can adapt well to many tank conditions

They are viviparous with internal fertilization. Females can store sperm from the males to fertilize later. They produce fingerlings in instalments over short periods. After the gestation period, which can vary between four to eight weeks, females give birth to the offspring that have already been formed (about 20 to 150 fish). They do not perform parental care and reproduce easily.

The male is smaller and more colourful than the female, in addition to having an adapted anal fin in the shape of a gonopodium. Females are bigger and plumper.

What do Molly fish eat?

They are omnivores. They will readily accept dry and live food, and vegetable matter must be supplied regularly.

Where do Molly fish live?

Mollies are found in North and South America. They typically occupy slow-moving tropical waters with loads of vegetation. They are highly resistant to salinity, which makes it possible to find them in environments with a small concentration of salts, such as river mouths.

They are very common ornamental fish in aquariums, they have different body conformations giving rise to several subdivisions such as the Black Balloon Molly and the Black Lyra Tail Molly. 

They are peaceful fish with other species, ideal for a community aquarium, but they can be aggressive towards each other when a larger number of males are introduced. The proportion of two or three females for each male should be maintained.

They spend much time cleaning algae from the glass and decoration, due to their need for vegetable components.

Other Algae eaters

–       Bristlenose pleco

–       Clown pleco

–       Twig catfish

–       Siamese Flying Fox

–       Siamese Algae eater

–       Malaysian Trumpet snail

–       Ramshorn snail

–       Nerite snail

–       Mystery snail

–       Amano shrimp

–       Cherry shrimp

–       Ghost shrimp

How to make this combination work

Angelfish and most of the algae eater species can make great combinations in a community tank. Some recommendations to successfully choose the algae eater species and set them together are:

–      Algae species should be identified, then algae eaters could be selected;

–       pH levels should match the species in the community tank;

–       Consider introducing them while the Angelfish is young, or with plenty of space for them to finely meet. Adult individuals tend to be more territorial and aggressive;

–       Try mutually suitable tank mates for the community;

–   Opt for peaceful medium-sized algae eater fish species.


In this post, we understood the relationship between Angelfish and some Algae eaters. We also discussed the algae eaters general biology and tank requirements.

If you have any thoughts or doubts, feel free to drop us in a comment below!

Frequently Asked Questions (FAQs): Angelfish and Algae eaters

Do angelfish get along with algae eaters?

There are several species of algae eaters. Most of them are good tankmates to Angelfish and they get along just fine in a community tank.

Do Angelfish and plecos get along?

Yes, most of the plecos species are very peaceful concerning the Angelfish. Thus, Plecos are great algae eaters to keep with Angelfish.

How many mollies should be kept together?

Mollies are schooling fish. Thus, they should be kept in groups of at least 6 individuals. Additionally, the female number should be greater than the male one.

Can Otocinclus go with angelfish?

Yes, Ottos are very amicable and peaceful. Thus, they can be easily set up as Angelfish tank mates.

What fish go well with Otocinclus?

Ottos get along with several fish species. They are great community tank inhabitants. Some of the Ottos tank mates are Angelfish, Cherry Barbs, Corydoras Catfish, Danios, Dwarf Gouramis, and Guppies.


Schaefer, S.A., 2003. Loricariidae – Hypoptopomatinae (Armored catfishes). P. 321-329. In R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brazil.l.

Burgess, W.E., 1989. An atlas of freshwater and marine catfishes. A preliminary survey of the Siluriformes. T.F.H. Publications, Inc., Neptune City, New Jersey (USA). 784 p.

Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalog of siluriform primary types. Zootax 1418:1-628.