Bird Families

Otocinclus sp


In Thai: นก แอ่น ท้องขาว, nok aen thong khaw

Binomial name: Collocalia affinis, Robert cecil beavan, 1867

The plume-toed swiftlet (Collocalia affinis) is a small bird in the swift family Apodidae. It is found on some eastern Indian Ocean islands, the Malay Peninsula, Sumatra, and lowland Borneo.

Its natural habitat is subtropical or tropical moist lowland forests. It was previously considered a subspecies of the glossy swiftlet.


The plume-toed swiftlet was described by the English ornithologist Robert Cecil Beavan in 1867 and given current binomial name Collocalia affinis. The type locality is Port Blair in the Andaman Islands. The specific epithet affinis is Latin for "related" or "applied". The plume-toed swiftlet was previously treated as a subspecies of the glossy swiftlet but was promoted to species status based on the results of a detailed analysis of the swiftlets in the genus Collocalia published in 2017.

There are five subspecies:

  • C. a. affinis Beavan, 1867 - Andaman and Nicobar Islands in the eastern Indian Ocean
  • C. a. elachyptera Oberholser, 1906 - Mergui Archipelago off the west coast of southern Myanmar
  • C. a. vanderbilti Rodolphe Meyer de Schauensee & Ripley, 1940 - Nias Island off the west coast of Sumatra
  • C. a. oberholseri Stresemann, 1912 - Batu and Mentawai Islands off the west coast of Sumatra
  • C. a. cyanoptila Oberholser, 1906 - Malay Peninsula, Sumatra, Natuna Islands and lowland Borneo


The plume-toed swiftlet is 9 - 10 cm in length with a square tail. The back and upper surface of the wings are uniformly dark greenish-blue with a moderate gloss. The throat and upper breast are dark gray merging into large greyish chevrons over the lower breast and flanks, usually becoming white over the belly. There is a tuft of small feathers on the, the rear facing toe. This species lacks a pale contrasting rump and has no white spots on the inner webs of the tail feathers.

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General information

Usually these fish are bred for their appearance. But Takashi Amano and other seasoned aquarists also purposefully use ototsinklus to clean out unwanted algae from the aquarium. If the algae gets out of hand in your tank, the catfish will work wonders by quickly bringing the ecosystem back into balance. We are talking specifically about microalgae that appear in the water column and on the walls of the aquarium. Otik does not eat aquatic plants, using them as a shelter.

Cleansing the surface of algae, ototsinkluses attach to it with sticky lips. In addition to oxygen dissolved in water, they sometimes need atmospheric air, after which they rise from time to time to the surface.

You don't need a lot of experience to keep ototsinklus, as they are not too demanding on environmental conditions. If you can keep your tank clean, most species will live for 3-5 years, reaching about 5-6 centimeters in length.

Living in nature

Otozinklus are native to South America. Their main habitats are the rivers of Northern Argentina and Venezuela. However, they are not in the largest Amazon River, which flows through the continent. Usually found in small streams or shallow bodies of water. Here they attach to the substrate or rocks in search of algae.

Most of their life is spent at the bottom of the river or on the leaves of large aquatic plants. They keep in groups in one area, completely devouring the microalgae on it, then move to a new surface rich in food.


Otozinklus are great for small aquariums because adults rarely reach 6 centimeters in length. The smallest species (Otocinclus tapirape) grows to approximately 3 centimeters in length. The largest species is Otocinclus flexilis, which can be over 6 centimeters long.

The body of the catfish has a simple cylindrical shape that tapers towards the front and towards the caudal fin. A strong mouth is located on the head, which is used to fix the fish on a hard surface.

On the left is a boy, on the right is a girl.

Representatives of the Loricariidae family differ from many other groups of catfish in that they have rows of "armor" made of strong scales throughout their bodies. This helps them protect themselves from predatory fish and tough substrates.

If you have an ototsinklyus catfish, how to distinguish a male from a female is an important question. Females are usually larger and brighter. This is most noticeable when viewed from above or below. Males are distinguished by a skin flap on the pelvic fin and a small contact organ near its base.

When it comes to colors and patterns, one look can be very different from another.


The Otocinclus catfish are usually calm in nature. These fish will never become aggressive towards other inhabitants of the aquarium.

Due to their small size, they can be easily eaten by predators and therefore are rather shy. To reduce stress in the aquarium environment, an artificial shelter should be built for them.

It is also useful to keep them not one by one, but with other members of their species (at least 4-6 pieces).

Otozinklus are usually active during the daytime, but, being frightened, they can switch to a nighttime diet and hide during the day, which is very inconvenient for aquarists.

Care and maintenance

In their natural habitats, these fish often attach themselves to boulders, gravel and other river bottom surfaces that contain small algae.

Although ototsinkluses can keep their tanks clean by eating algae, it is still important to change the water weekly or at least every two weeks. This helps prevent nitrate and ammonia build-up and maintain a healthy living environment for your fish.

Since catfish live mostly on the bottom, choose a sandy type of substrate for your aquarium and avoid rougher surfaces that can damage your fish's skin when they graze on the algae.

Scratching the surface of the catfish can lead to infections and other diseases, so efforts should be made to ensure the safety of these bottom dwellers. Although they have "armor" on their belly, you shouldn't rely on it.

Properly selected aquarium decorative elements will serve as refuge for these fish when they are tired or stressed. Large rocks can be used to create cave shelters for your fish to rest when they need it.

The minimum size for an Otocinclus aquarium should be about 40 liters. This is enough for a habitat of 4 to 6 catfish. If the volume of the aquarium is larger, the number of individuals can be increased.

Types of ototsinklus

There are numerous varieties of Otocinclus catfish. Let's take a look at some of the more popular aquarists:

Otozinklus ordinary - having a golden color with a black stripe along the body and dark spots, reaching a length of 6 centimeters.

It is easy to confuse with ordinary, characterized by more pronounced spots.

It has an elongated yellow body with pronounced brown spots.

Characterized by a pale color with a distinct longitudinal black stripe.

With a dark stripe against the lemon-yellow background of the rest of the body.

Zebra-like color, usually up to 4.5 centimeters long.

Otozinklus speckled - having a more pronounced spotted structure than all other representatives of the genus.

With a grayish tinged body, with a darker longitudinal line characteristic of most ototsinkluses.

With a high dorsal fin and a rhomboid spot at the tail.

With a contrasting arrangement of bright dark spots on an almost white body.

Five-centimeter - with patterned spots all over the back.

Maria is completely spotted on top.

With a light brown back and a yellowish abdomen.

Solid dark top.

C is characterized by a convex back, usually not reaching 3 centimeters in length.

Longitudinal pattern over dark stripe.

Habitat and Habitat

South America: Amazon basin, endemic to Brazil. Inhabits the rivers of the state of Rio de Janeiro.


The color is buffy-golden, from the beginning of the snout through the eye, along the lateral line to the caudal fin, inclusive, there is a black wide stripe. On the caudal peduncle, the stripe turns into a rounded spot, often divided into two parts. Belly white

The head is of moderate size, the snout is elongated and rounded. The eyes are large. There are large "ear" holes on the sides. The mouth is a kind of suction cup. The body is elongated, slender, tapering towards the caudal peduncle. The body is covered with small bony plates. The dorsal fin is high, oblong, with one rigid ray. The pectoral and pelvic fins are small, colorless. The adipose fin is absent, the caudal fin is wide.


The minimum aquarium size is 60 cm.

The ideal conditions are a stable, healthy aquarium, densely planted. Driftwood and stones, nooks and crannies among plants. Oxygen rich water with little movement. A lot of food - soft algal fouling.

There should not be a lot of organic contaminants in the water. Filtration must be complete and of high quality. The quality of the water should be high: ammonium is not detected, nitrite is 0, nitrates are less than 10 mg / l.

Water parameters:

Temperature: 21 - 27 ° С
pH: 6.0 - 8.0
Hardness: 5 to 19 ° dH

Weekly change of 30-50% water.

With a low quality of water, they die from mass destruction by bacteria.


Quarantine treatment using water acidified with peat and methylene blue to increase the antibacterial effect.

It is often said that individuals caught in the wild die in an aquarium in the first few weeks. It is necessary to adhere to certain rules for adapting to the aquarium. The main thing is not to put the Otocinclus in a large aquarium with plants right away. This is especially important if the aquarium is "large" (water surface area is more than 1 square meter).

It is better to use the following guidelines:

Use a small aquarium of 30-60 liters without soil, using simple fish (guppies, platies, etc.). Install two air-lift filter sponges. This filtration method was chosen for several reasons: it is the best option for an aquarium without soil, good oxygenation of the water does not create a strong flow, and because otics like to eat sponges just like the walls of the aquarium. The optimum temperature is 25-26 degrees.

Place 6-10 fish in this tank. Feed with cereals, some bloodworms and spirulina. Do not feed fresh vegetables yet - you first need to quickly restore the strength and health of the fish. The fact is that during the transportation they were most likely poorly fed. In addition, when you start in a good plant aquarium, there will likely not be enough food for a flock of otics. Feeding your fish well for a while in a small aquarium will greatly increase their chances of survival.

Intestinal worms and gill flukes (Dactylogyrus - gill flukes) can be fatal to fish and are the number one problem for importers. The newest drug from JBL Gyrodol - helps against gill (Dactylogyrus), skin (Gyrodactylus, Trematoda), blood (Schistosoma) flukes and even tapeworms (Cestoda). The Praziquantel it contains opens the calcium channels in the worm's skin, they die quickly and are excreted in the feces (tapeworms only) without poisoning the fish. Eliminates all parasites in 6 hours. Not to be confused with JBL Gyrodactol! Use food with medicines for parasites for at least a week. Ichthyophthirius infection can be avoided by using malachite greens.

During quarantine treatment DO NOT use: Salt, Copper or Insecticides (Masoten, Neguvon, Dylox, DTHP) - they can be killed by these medicines!

For long-term transportation, use an ammonia neutralizer.


Since these fish are herbivorous, they need a large amount of food and the abdomen should always be full. It is a big mistake to think that they can live without additional feeding. Several individuals in a matter of days cleanse a 300 liter aquarium of algae and start starving! Most often, they die precisely from a lack of food in an aquarium that is too "clean" of algae.

There are reports that they chase other fish (discus, scalar, etc.) eating mucus from their skin: they probably eat microorganisms living on the mucus.

If there is not enough feed, give them blanched vegetables (in the microwave oven - 30 seconds in a bowl of water). You can give zucchini (young zucchini), cucumbers, lettuce, peas, spinach and cabbage, attaching them with a clothespin on a suction cup to the walls of the aquarium or with an elastic band to a stone. Leftovers of vegetables that have not been eaten must be removed on time (two days maximum), otherwise they will spoil the water in the aquarium.

Dusko Bojic ( notes that the best food for them is blanched zucchini:

“It’s known if Oto ignore catfish pills and dried seaweed, and ignore most other vegetables like lettuce, spinach, cucumbers, etc. Zucchini is the best proven food. Boil the zucchini for 2 minutes before feeding it. Put the zucchini on the bottom, or even better on a driftwood where Oto will quickly find them. Do not leave the zucchini for longer than two days, but not less than one day. "

• It is believed that they need driftwood - perhaps they eat the microorganisms that settle on them.
• Potato chips and tablets with herbal supplements and spirulina are also good food you can buy at the store.
• If they ignore all types of food, then there is enough algae in the aquarium for them.
• This species is most active at night, so feeding should be given in the evening, after turning off the lights.


Sometimes the fish reproduces unnoticed by the owner, especially in a large aquarium with dense vegetation. This becomes noticeable only due to the fact that their number has become more than a month ago. This is especially facilitated by dense thickets of small-leaved plants and moss.

After two to three weeks, the fry become like an adult.

Eggs are laid several times over the summer, without prior increasing water changes.

The stimulus for spawning is abundant protein feeding - brine shrimp nauplii, bloodworms, tubifex, the presence of microorganisms in the water (Euglena viridis - "blooming water").


The aforementioned 30-60 liter aquarium without soil with a filter sponge is an ideal spawning and nursery aquarium. Plant more Javanese moss and small plants. Place a female and at least three males there. Regular water changes of 25-30% per week. After spawning, spawn the producers.

The female actively swims around the aquarium, pursued by the male. In the end, she presses against the anal fin of the male and then sticks on the underside of the leaf from three to six eggs, or scatters eggs in small portions in the secluded corners of the aquarium on stones, glass, broad-leaved plants. The male follows her, fertilizing the eggs. During one spawning, 60 or more eggs are laid. The caviar is sticky, transparent, slightly yellowish. If the fish have laid eggs in a common aquarium, you can cut off the leaves on which the eggs have adhered and move them to the incubator.

Another source - Water parameters: pH 6.5-7, hardness 4-10 °, temperature 20-22 ° C. Spawning usually occurs early in the morning. The female takes the male's milk into her mouth and pours it on the cleaned, brightly lit surface, sticking eggs to it, which makes it possible to fertilize almost 100% of the eggs. Productivity is up to 130 eggs. After spawning, the producers are planted and the temperature in the aquarium is raised to 26-28 ° C. To avoid the appearance of mold fungi, methylene blue must be dissolved in water until a faint blue coloration.


The water level in the caviar container should be at least 5 cm. The temperature is 24-26 degrees.
Add methylene blue to the water so that the caviar remains visible.
Twice a day, change 80% of the water to fresh water with the same amount of methylene blue.
When the time for hatching of the fry is close (after two to four days, depending on the temperature), the eggs can be blown out so that the fry are detached from the shell.
After hatching, reduce water changes to 25-30% per week, without adding methylene blue.
After a couple of days, their yolk sacs are emptied - at this moment, you need to start feeding the fry.

Growing fry

Starter feed for ciliates, seaweed, spinach, brine shrimp, crushed Tetra Tabs.
Frequent small water changes to reduce nitrate levels and clean the bottom of feed residues.
When changing water, put a net on the hose / siphon so as not to suck in the fry.
When the fry swim, launch the snails - they will eat the excess food from the bottom, and their excrement is good food for ciliates.
Keep a separate container in the sunlight so that water blooms in it, then use it as food for the fry (euglens and other unicellular organisms will multiply in it).

Notes (edit)

All types of Otozinklus are suitable for keeping in an aquarium with plants. There are many varieties, differing only in minor differences in color and pattern of the pattern on the caudal fin and head, so it is very difficult to determine which species you have. There is no particular sense in this - they are all equally effective. The most commonly imported species are O. affinis, O. mariae, O. macrospilus, and O. vittatus.

They have thorny dorsal and pectoral fins, transplant carefully - with nets with a fine mesh and lower them into the water by twisting the net so that they come out on their own.