If you want a small, peaceful, bottom-dwelling fish and proven algae eater for your fish tank, then the Zebra otocinclus (Otocinclus cocama) might be what you’re looking for. These sweet little fish make an unusual addition to a freshwater aquarium, but they do have a reputation of being difficult fish to keep.
In this guide, we take a closer look at these delightful, peaceful fish and explain how to care for them.
The Zebra or Tiger Oto only appeared in the trade in 2000. Officially described and renamed by Roberto E. Reis, this Otocinclus species comes from Peru, specifically the Ucayali River and the Marañón River.
In the wild, the Zebra Oto inhabits mid-sized creeks, tributaries, and small ponds with clean water. These timid fish tend to gravitate to areas of dense marginal vegetation where they feel most secure.
Sadly, this recently discovered species is currently categorized on the IUCN Red List of Threatened Species as “endangered,” largely due to harvesting for the trade. At the time of writing, there is little information regarding wild population, and it’s not known whether those populations are diminishing. There are no current conservation projects in operation to protect the Zebra Oto.
Otocinclus cocama has a similar body shape to other species of the genus.
Otocinclus catfish have armored bodies and sucker mouths to strip green algae from surfaces within their tank. They are marked with striking black and white markings, hence the common name of Zebra or Tiger Oto.
Telling males and females apart is difficult, although female fish are usually smaller and plumper than males. Mature male fish also have pointed genital papillae.
Zebra Otos are tiny, reaching only around two inches or so at full maturity.
These beautiful fish have a life expectancy of five to nine years if properly cared for and given the pristine water and high-quality diet that they need to thrive.
Zebra Otocinclus are active river fish, and in aquariums, they spend much of their day foraging around the lower margins of the tank for plant matter, algae, and other food scraps.
These are shy, timid fish that need plenty of cover, as they like to hide away when they feel threatened.
Compatibility And Tankmates
The Zebra Otocinclus is a peaceful creature that makes an excellent addition to a community aquarium.
Since these are such nervy, timid fish, the ideal community fish to pair them with are similar-sized, peaceful species, including rasboras, Corydora catfish, dwarf cichlids, and tetras. Freshwater shrimp and snails can also do well with Otocinclus cocama, as long as there is enough fresh algae to go around and you include algae wafers and fresh vegetables in their diet.
If you have a small nano tank, you might want to consider keeping an exclusive school of six to eight Otos.
As schooling fish, they need the added security of safety in numbers, and they can’t tolerate being hassled by larger fish or bullies, especially at feeding times.
Fish Species to Avoid
As previously mentioned, large species of semi-aggressive fish should be avoided. As the Zebra Oto is a shy fish, bossy, over-attentive species will put stress on them. Stress leads to a compromised immune system and almost always makes fish susceptible to health issues and outbreaks of disease in the tank.
Also, since they are incredibly small fish, it’s safest to avoid any fish that are large enough to view the Otos as a potential meal.
A high-quality diet is essential for the health and wellbeing of any fish species. In the case of Zebra Otos, it’s important to remember that the vast majority of specimens in the trade are wild-caught, so you must try to replicate their wild diet as closely as you can.
What To Feed Your Zebra Otocinclus
Otos are omnivores. In their wild environment, Zebra Otocinclus eat a varied diet of green and brown algae, plant and vegetable matter, zooplankton, micro worms, and general detritus.
In the aquarium, you can feed your Otos a range of quality fish foods including algae wafers, sinking catfish pellets, and frozen meaty proteins such as daphnia, cyclops, bloodworms, and the like. These fish also enjoy the inclusion of fresh veggies, especially blanched zucchini and slices of cucumber.
How Much and How Often to Feed Zebra Otocinclus
It’s generally best to feed your fish twice a day. Unlike many catfish species, Otos are diurnal, so you can feed them in the morning and the evening.
Ideally, you want to offer your fish just enough food to keep them busy for a few minutes at each feed. Don’t overfeed the fish! Overfeeding can cause health problems, and leftover food will gradually decompose in the substrate, polluting your water and placing an additional load on your filtration system.
If you’re not at home at the times when you want to feed your Otos, get yourself an automatic fish feeder with an integral timer. These devices are not expensive, but they are a godsend to the busy fish keeper! Simply load the feeder with the correct quantity of food and set the timer to dispense the meal at the appropriate time.
Zebra Otocinclus can be tricky to care for until they have settled into their tank environment, and the mortality rate tends to be depressingly high. However, if you provide the fish with clean water and the conditions they need, you can successfully keep these attractive fish.
These delicate little fish tend to die off within the first few weeks of being introduced to their new aquarium home, no matter how perfect the water conditions in the tank.
Well, virtually all Zebra Otos in the trade are wild-caught by fishers who poison their water with cyanide, which stuns the fish, enabling their captor to scoop up the helpless creatures. As if that wasn’t stressful enough, the fish are then transported, shipped, and delivered to stores, often traveling vast distances.
That experience, combined with the subpar conditions in which the fish are kept weakens their immune systems, leading to bacterial infections and death.
Additionally, the Zebra Otocinclus has a symbiotic relationship with the bacteria in its gut, digesting cellulose found in the cell walls of plants and algae. If the fish don’t have access to the right food source for even a few days, that bacteria can die, and the fish can’t absorb the nutrients it needs to survive.
So, when you buy these fish from your local fish store, always remember to ask whether the fish are wild-caught or commercially bred. You also need to know how long the fish have been at the store. Take a close look at the specimens in their tank at the store to make sure they’re grazing on algae.
Since these are quite small fish, they can be kept in a 20-gallon aquarium, although a larger tank is better.
Be wary of overcrowding your fish, as that causes poor water quality and can overload your filtration system. If the water in the tank is dirty, they will eventually die.
As with any fish species, you need to make sure that the environment in the tank replicates their natural home as closely as possible.
Zebra Otos tend to do best in a mature aquarium with plenty of algae.
Since Otos spend a lot of time foraging around the bottom of the tank, it’s best to use a soft, sandy substrate so they don’t sustain injuries from pieces of sharp gravel.
As previously mentioned, these Otos are shy and need an established aquarium with plenty of cover to feel secure. In the wild, the water’s edge is lined with aquatic vegetation where they take cover and hide from predators.
In the aquarium, you need to provide plenty of lush planting, smooth driftwood, and stones where large amounts of algae can grow. It’s good to have a few slate caves, too.
In the wild, Otocinclus cocama lives in streams, larger rivers, and other bodies where the water is crystal clear. So, your tank needs an efficient, well-maintained internal water filter system with a medium flow rate.
For your Otos to thrive, you need to keep them in stable water conditions and within suitable tank water parameters.
Zebra Otocinclus are tropical fish that need a water temperature of between 72° to 77° Fahrenheit.
Water Hardness and pH Range
The fish enjoy soft, slightly acidic water with a pH between 6.0 and 7.2 and a hardness of up to 12 degrees.
Zebra Otos don’t have any specific lighting requirements. However, since they are shy, they seem to prefer an environment where the lighting levels aren’t too bright.
As these fish are sensitive to water conditions and used to living in free-flowing conditions where the water is naturally kept clean and well-oxygenated, you’ll need to keep on top of your aquarium maintenance regimen.
Vacuum the Substrate
As part of your water change routine, use an aquarium vacuum cleaner to get rid of any uneaten fish food, solid fish waste, and rotting plant matter that’s buried deep within the substrate. Pay particular attention to areas around the base of plants, the tank corners, and underneath the filter box. If you fail to do that, the ammonia levels in the tank will increase, poisoning the water and your fish.
You also need to trim off any dead plant leaves and prune back overgrown areas.
Partial Water Changes
Partial weekly water changes of around 15% are necessary every week to remove excess nitrates. That’s essential for Zebra Otocincus, as they need pristine water to thrive.
You also need to test the water quality, using an aquarium water test kit to make sure that you have zero ammonia and nitrites in the water and nitrate levels are below 20ppm.
If your aquarium water is to remain clean and healthy for your fish, you need to rinse the filter media in dirty tank water once a month. That will remove any sludge that could block the media and prevent the flow of water through the filtration system.
Replace spent filter media when required in line with the manufacturer’s directions.
Health and Disease
Again, the main issue with Zebra Otos is that they are usually wild-caught. As described earlier, that process is hugely stressful.
However, Otos are also vulnerable to the most common diseases that affect aquarium-kept fish.
Signs of Good Health
Once your Otos have settled in, they should be fairly lively, hanging out together in loose schools. However, it’s also normal, healthy behavior for them to hide among plants or in caves.
Zebra Otos also spend quite a lot of time using their suckers to graze any algae growing on surfaces within the tank.
Potential Red Flags
There are a few things to watch out for that could indicate that all’s not well with your fish, including:
- Loss of appetite
- Not schooling with conspecifics
- Swellings and ulcers on the skin
- Flashing or rubbing against tank decorations and the substrate
Common Health Issues and Treatment
Here are a few of the most common health conditions that can affect Zebra Otocinclus.
White Spot Disease
White Spot Disease is also often called Ich or Ick. Ich is probably the most common problem that affects aquarium fish.
The condition is caused by a tiny parasite that attaches itself to the fish’s body, gills, and fins. Look out for tiny white dots sprinkled across the fish that look like grains of salt. Fish with Ich also flash and flick their bodies against anything solid in the tank.
You can treat this condition by raising the water temperature to 82° F for a few days and treating the tank with White Spot medication.
Ich is generally caused by stress. The parasites are usually present in the aquarium but non-problematic until a fish is weakened by some other disease or stress. So, make sure that your water is clean and within the correct parameters for the Otos, feed them a high-quality diet, and be aware of any bullying behaviors by tankmates.
Bacterial infections can take many forms, affecting fish externally and internally. Usually, injured fish are the most prone to attack by bacteria. Watch out for ulcers, missing scales, ragged fins, and reddened patches on their skin, all of which could indicate a bacterial infection.
Isolate the affected fish in a quarantine tank and treat the water with antibacterial medications. Again, check your water quality and carry out a water change on your main tank before returning the treated fish.
“Flukes” is an umbrella term for external parasites, often visible to the naked eye, attached to the fish’s body or gills.
Since most Zebra Otos are wild-caught, the chance of unwanted passengers hitching a ride into your tank is fairly high. Flukes can be successfully treated with over-the-counter medication that you can buy at your local fish store.
Breeding Zebra Otos in the home tank is challenging, to say the least! However, there are a few reports of successful Zebra fish breeding by some hobbyists.
They are egg-layers, depositing their eggs on the underside of leaves or sometimes on the aquarium glass. Both parents clean the spawning sites prior to breeding, and it’s thought that they spawn in a “T” position rather like that of Corydoras catfish.
As the fry are incredibly tiny, feeding them is the main challenge facing the aquarist, and, sadly, most of the babies die of starvation or are eaten by other fish in the aquarium.
Most fish stores do not stock Zebra Otocinclus routinely, although your local outlet might be able to order some for you. However, you can usually buy them online for around $15 each.
I hope you enjoyed our guide on caring for the rare and beautiful Zebra Otocinclus.
If you keep a group of these delicate little fish and managed to breed them successfully in your home aquarium, we’d love to know! Tell us about your Otos in the comments box below, and please share this article if you enjoyed it.