Algae is a common problem in aquariums. It flourishes anytime there are enough nutrients and light to meet its needs. There are a lot of ways to combat algae; some revolve around making sure algae doesn’t get what it needs to grow. Others include targeting outbreaks with manual removal, or spot treatments with hydrogen peroxide.
Other things we can do:
- make water changes to reduce the waste products they feed on
- reduce our fish stocking density
- check our lighting fixtures & bulbs
- put timers on our lighting so doesn’t run longer than needed to ensure plant health
- introduce plants that will compete with algae for the available nutrients
- add inhabitants to the aquarium who love to munch on algae
We’ll talk about some of those other methods in future posts but for now, I want to introduce you to a few of my favorite algae eating critters for planted aquariums.
Note: the list of suitable algae eaters can vary depending on your tank setup and your fish selection. I have smaller peaceful fish including Rasboras, Neon Tetra, Rummy Nose, Pencil Fish, Celestial Danio, Guppies and a few types of shrimp in a densely planted tank. My recommendations below are based on this type of community tank.
Otocinclus CatfishOtocinclus are small peaceful catfish native to South America and often referred to as dwarf suckers, oto cats, or just plain otos.
I’m not sure what it is about otos, but like a lot of people with planted tanks I find them fascinating. I started with three in my 29 gallon and now am up to about eight. They scrape at the algae on the glass, suck at algae on the plant leaves and eagerly tackle any other food scraps in the tank. They are good tankmates for a variety of peaceful fish. They like clean but established tanks, with plants, some algae and biofilm.
Otos do best in established planted tanks, with peaceful tank mates and in groups of three or more. Remember that you need to make sure otos have enough to eat. People sometimes think suckers and catfish survive just on scraps and I have seen oto cats get skinny and die from neglect.
Next on the list of algae warriors are the shrimp. I have a few types in my tank but two of the most productive algae grazers in my tank are the Amano and the Cherry shrimps – members of the Caridina & Neocaridina genus respectively (note: there are other family members and color variations of these shrimp species that may be just as effective, these are the ones I have in my tank).
Amano ShrimpThese are hardy and active shrimp and a good choice for first-timers. They tend to grow bigger than Neocaridinia and while I have heard anecdotally that big shrimp may prey on smaller species I have not seen this behavior; some of my Amanos are 1 1/2″ long and I haven’t seen them bother the tiny baby Cherry shrimp in my tank.
Having said all that – they are greedy! They are always on the lookout for food and when I drop tablet food into the aquarium the Amanos will grab it and try to drag it into a hidey-hole so they don’t have to share.
One thing to keep in mind with both the Amano and Cherry shrimps is that if you have lots of other food in the tank they won’t be as enticed by the algae. Why? Well just imagine if I gave you a choice between your favorite food, and a small hard biscuit that I told you had the same nutritional value – which would you rather eat? Don’t overfeed, and you’ll notice that as the day goes on the Amanos will be furiously picking at many types of algae and biofilm while they wait for your next feeding..
Cherry ShrimpCherry shrimp are a peaceful, hardy and industrious shrimp from Taiwan which is very popular among planted tank enthusiasts. There are a wide range of color morphs that have resulted from selective breeding and culling which include red, yellow, orange, green, blue, violet, black. Within those colors you’ll find yet more intense and brilliant variations with names like Blue Diamond or Sapphire, Bloody Mary and striped or patterned varieties like Rili. They breed readily and can be a fascinating addition to an aquarium.
Cherry shrimp are omnivores that feed on biofilm and algae. Like the Amano they’ll eat all of your prepared food gladly, so if you want them to help control your algae you’ll need to find a balance. I haven’t verified this with any sophisticated testing but if these things were as big as Amanos I think they’d eat twice as much algae. It is pretty amazing to watch how fast their tiny legs pick and shove food into their mouths.
Zebra Nerite Snails
The Nerite Snails that are commonly sold for freshwater tanks are interesting and hard working. They are hardy though they seem to have a relatively short lifespan in freshwater aquaria of about a year.
One of the key selling points of these snails is not only how much algae they eat but that with their strong rasping teeth they are able to remove the harder spot algae from the aquarium glass. Another benefit of these snails is that they need brackish water to reproduce so you don’t have to worry about hordes of babies – unless you are adding salt to your aquarium. I’ve read that they can lay sesame seed sized eggs, attached to various objects in the tank but I have not had that occur in the 8 months I’ve had them.
Keep in mind that since algae and biofilm are primary food sources for these snails they will do better in an established tank with some algae growth. Probably best not to introduce them into a brand new tank.