Algae can become a problem in the aquarium if left unchecked or uncontrolled. Luckily, in the planted aquarium there are a few species that can help out, but their suitability depends on the type and size of the aquarium you have, and what other species already inhabit the tank. For the most part, these algae eating fauna can fit any tank. Here is a quick guide to a selection of suitable fish and shrimp that help fend off algae.
Otocinclus spp. are one of the most popular fish used to help in the control of algae. There are a few species that I have seen available here in the UK, and these are O. vestitus, O. affinis and O. macrospilus. Most 0tocinclus sold are caught in the wild. When these fish are imported, they are often starved during the transport stages, and so many tend to die off even before they reach the wholesaler/retailer. Because of this, you need to be careful when choosing your Otos. A fish with a nice, rounded silvery stomach should be fine, as this indicates that they have been fed on adequate foods since their import and should continue to do so. All too often though, Otos found in aquatic shops are very skinny and suffering from malnutrition. This is why they are often considered to be tricky to keep, and can die off during acclimatisation.
Most Otocinclus will grow to around 2 or less and eat a wide range of algae, so making them a great choice of algae eater in large or small tanks. They should really be kept in groups of around 6 and will often stay close to each other in the aquarium. This is when they are at their most effective in a planted aquarium. In my experience they are very gentle with aquatic plants, and will not even damage soft leaved plants while feeding on the algae.
Siamese Algae Eaters (Crossochelius siamensis), or SAE as it is often written, can grow much larger than the Otocinclus (up to 6) and because of this are suited to the larger aquarium only. I would suggest a minimum being a 36 tank to keep these fish at their eventual size. I have found they can be a bit boisterous and may uproot newly planted carpet plants and disturb substrate, which is a problem if it clouds easily. Like the Ottos, these algae eaters are said to eat a variety of algae types including black beard algae, or BBA. This is a common problem in planted aquaria and it is sometimes attributed to low CO2 in the water. There is often confusion between this species and the Chinese Algae Eater, or CAE, as they look very similar. One difference between them is the number of barbels, the SAE having one set and the CAE having 2 sets.
The Amano Shrimp (Caridina denticulata, formally japonica), or Yamato Shrimp as it is sometimes known, was brought into popularity by Takashi Amano in his search for the perfect algae eating shrimp. He tested many shrimp, but eventually settling on the Amano Shrimp, a Japanese native species and ordering several thousand from the supplier! They will eat most types of algae and are very effective at their job. They will reach around 2 and are suitable to most size aquariums. One problem with keeping shrimp in the aquarium is that you will need to be careful about other occupants. Large fish such as Angelfish and Discus are likely predators of shrimp.
Neocaridina denticulata sinensis
Cherry Shrimp (Neocaridina denticulata sinensis) are another popular shrimp choice for the aquarium, mainly because of their size and colour. Female Cherry Shrimp are bright red, whereas males can be slightly drab in comparison. These shrimp are smaller than the Amano Shrimp, and I havent had any grow past 1. You will need to be wary of filter inlets due to the small size of the shrimp. They will readily breed in the average aquarium, given plenty of cover such as mosses and few predatory fish to eat the young. Even Tetras will snack on babies. Sometimes when you clean the filter during maintenance, you can find live baby shrimp that have been sucked in and are living off detritus or algae in the filter.