Golden Oto (Ottocinclus Affinnis)
Native Location: South America
Size: 2.5 – 5 cm (1 – 2 inches)
Temperature Range: 22 – 26 (72 – 79)
Preferred pH Range: 6.8 – 7.5
Minimum Aquarium Size: 38L (10 gallons)
Potential Tankmates: Freshwater Angelfish, Cherry Barbs, Guppies
Care Level: Beginner
Golden Otos are often misidentified, as their features are common to Otocinclus (Otocinclus Vittatus). A great beginner fish that also doubles as part of your inner tank, algae clean-up crew!
An Otos follow a strict herbivore diet mainly consisting of algae. But algae can run out fast for several reasons if your tank is well maintained. So, you will need to introduce other alternatives. Try algae wafers which, when introduced into the water, will disappear in a few hours. Green vegetables are also excellent alternatives, like spinach, lettuce and zucchini. Depending on how many Otos you keep, you will need to chop off a small piece or two and drop them in the tank. Make sure it sinks to the bottom and that you remove any remaining scraps 24 hours later to reduce waste in the aquarium. While you have to worry about Otos getting enough food, also be cautious about overfeeding them. Otos are small and peaceful bottom-dwellers. Meaning they will get along with many other gentle species that occupy the mid to top sections of the aquarium. Their tiny stature can make them easier targets for larger fish.
They are great social creatures and need to be part of a group of at least four but will always prefer having more friends. As they are bottom-dwelling fish, the substrate will need to be fine gravel or sand to prevent injuries. Coarse grains can scratch their bodies and lead to health problems. They will also need shelters if they find themselves stressed. So, create little cave and crevices and have live vegetation. They are unlikely to eat your plants. These will also add more services for algae to spread over (perfect for an algae eater.)
A Golden Otos colourings are closer to gold (hence the name) and less brown like the common Oto. It can be a task to tell the sexes apart. The best chance you have of noticing a difference is viewing them from above. From there, you should be able to see that the females are bigger bodied. Otos are not the easiest fish to breed in captivity. You will need some luck, and conditions more than perfect. Raising the temperature, a little should help, but do not exceed 26℃ (79℉). When they are ready to mate, males will chase females around the tank. Fertilised eggs are distributed in small bunches on surfaces around the tank. As Otos are herbivores, they will not eat their fry.