Bob Mehen helps one of our readers to successfully introduce dwarf suckermouth catfish into their aquarium.
I would like to add a group of Otocinclus catfish to my 90cm (36”) planted tank. I've tried keeping these fish before on two separate occasions, but numbers gradually dwindled. Looking back, I'm not sure my tank was mature enough then.
I've read several times that these small catfish often get starved during shipping. The tank is 12 months old now so I think there should be plenty of natural foods present.
Before I add them again, I wondered if it was worth setting up a quarantine tank. This would allow me to target feed them before introducing them to the main tank. If so, how should I set this up, and how soon before I buy them, as I suspect the quarantine tank will need to have some algae present?
What size of tank would I need to ensure water quality for 6-8 individuals? Which foods are best to offer them at this early stage and how often should I feed them?
These are the only fish I've ever had problems with and it's sad, as they're among my favourites.
All photos by Shutterstock
STEVE BEESLEY
Bob's advice on Otocinclus care
You are correct, Otocinclus catfish, like most tropical fish, often don't have access to food before transport. This helps to prevent them fouling the small amounts of water in their fish bags.
The problem is that otos are a grazing species which feed almost constantly on low nutrient foods like algae and biofilms. This sudden cessation of food can cause problems at the other end of the importation process. Added to this, their small size makes it harder to check for classic 'pleco' signs of health issues such as sunken bellies and eyes. Although, healthy oto should have a nicely rounded abdomen as pictured below and this can be seen when they are on the aquarium glass.
Related article: Keeping Otocinclus catfish in the aquarium.
With regards to setting up a quarantine tank, it needn't be large. Leave the tank near a window or with the lights on for at least 12 hours a day for a few weeks before the fish arrive. This will give it a chance to get a good coating of algae growing. An air-powered sponge filter is also a good choice as when mature it will add a grazing source to the tank.
These hungry algae eaters will soon take care of the natural algae bloom, so offer supplemental foods as well. Feeding Otocinclus slices of courgette or cucumber alongside prepared foods, such as algae wafers or Rephasy Super Green often works well. You can weigh down slices of vegetables in aquariums using seaweed clips or metal weights.
Related article: The 10 best algae eaters for tropical tanks.
The filter can be rapidly matured by squeezing the new foam in a bucket alongside a mature foam from your main tank’s filter. This transfers beneficial bacteria from one filter to the other. Do this the day before you add the fish, as there will not be food for the bacteria until you add the fish.
As always, you must keep a close eye on the water parameters to ensure there are no sudden spikes. Use a good quality test kit to check regularly for ammonia and nitrite and perform a water change if they are above 0.
However, at a year old, your tank is certainly mature. So it may be worth just adding them to the display, especially if your shop has fed them up a bit before you buy them. Just make sure there is adequate supplementary food available.
You mention that this is a planted aquarium, but adding even more live plants can also be useful. Aquatic plants offer more surfaces for algae to grow in the aquarium for them to graze on.
Related article: 5 easy and beautiful stem plants for your aquascape.
Otocinclus Top Tip
When buying Otocinclus, it’s often best to leave the fish in your local shop for a couple of weeks after import. Ask to see them feeding before you buy them. Healthy otos are enthusiastic feeders and a slice of courgette or cucumber placed in the sales tanks should be smothered in healthy fish, all nibbling away.
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