There are a number of factors that determine what and how many fish you can keep in any given aquarium, and there is a lot of conflicting information on the internet. Some sources claim it is the volume of the tank, some say it is the surface area of ​​the water, some say it is the physical dimensions of the tank, and some say it depends on the filter system. To some extent, all of these factors influence the number and type of fish you can keep in an aquarium.

The biOrb and biUbe have another factor that must be considered. Instead of the standard gravel used in the bottom of fish tanks, these aquariums have ‘ceramic media’. This ceramic medium resembles gravel and varies between 10mm and 18mm in diameter. It is very porous which allows the bacteria necessary for the biological element of the filtration system to develop. It is critical to the operation of the biOrb and biUbe tank and should not be removed.

Why does this affect the fish I can keep?  

Ceramic media, compared to standard aquarium gravel, is very sharp and this makes it unsuitable for bottom-feeding fish. The vast majority of bottom-feeding fish have a soft underside, which is not well suited to coarse ceramic media.

What kind of fish feed on the bottom?  

In general, loaches and catfish are bottom feeders. If you’re in a pet store and there are no labels on the tanks, it’s pretty easy to identify bottom-feeding fish, even if they’re not on the bottom. The vast majority of bottom-feeding fish will have their mouths tilted downward. Even if a fish is stuck to the side of the aquarium, it would still be classified as a bottom feeding fish and not suitable for biUbe or biOrb. If the reason you want to keep a catfish or loach in your tank is to add something different to the “normal” fish, then perhaps you could consider getting some shrimp. There are many different types; Cherry Shrimp, Ghost Shrimp, Amano Shrimp… They make fascinating watch, clean up a lot and make a great addition to any aquarium.

Is there anything else I can’t keep?  

Even the largest biOrb isn’t big by normal standards, so keeping any fish in it that eventually grows larger than 1.5 inches (about 38mm) isn’t going to have a particularly happy life.