BiOrbs are very popular aquariums and come in a number of sizes including 15, 30, 60 and even 105 litre volumes. Their spherical shape, acrylic construction and low voltage lighting make them popular with new fishkeepers and they are leaders in Lifestyle design, fitting perfectly into any room. But how many fish can you keep in each one?

BiOrb Classic 15 LED

At just 15 litres volume or just under four UK gallons, the BiOrb Classic 15 is the baby of the range. It’s only 12”/30cm in diameter so tank length and volume do restrict what you could keep in it. A Single Siamese fighting fish, Betta splendens, would be a good choice for this nano tank as male fighters need to be kept on their own. The pairing would look great and would be low maintenance. You’d need to add a heater though.

Opt for live plants like Java fern, Anubias and Java moss, which are slow-growing, easy to keep and low maintenance. They’ll aid water quality too. 

Or if you want something novel and different how about freshwater shrimps? Available in many colours including red and white, orange, yellow and even blue, shrimp of the genera Caridina and Neocaridina are easy to keep, easy to breed, collectable, and they eat algae. And their tiny size makes them perfectly suited for small tanks like the 15 litre BiOrb.

BiOrb Classic 30 MCR

The 30 litre model was the original BiOrb size when it was invented by Reef One. At 15”/37.5cm diameter it is only 3”/7.5cm wider than the 15, but holds twice the volume at 30 litres capacity. 

A tank of this size is capable of holding a community of small fish once mature and could be set up as a temperate (unheated,) tank or a tropical one. 

Suitable temperate species include White Cloud Mountain minnows, available in natural, golden or even long-finned form, and Zebra danios, also available in natural, golden and longfin. BiOrbs come with multi-stage filtration which includes a very large biological filter.

This means that once mature you could add five White Clouds and five Zebra danios, along with shrimp and snails. If you want to stay temperate but crave something with a bit more colour, Variatus platies would be good (up to five,) along with five Glowlight danios, Celestichthys choprae.

Heat it up

There are lots of small, tropical fish that could be kept in a BiOrb if a heater was added. Heat the water to a constant 24C and you could opt for Neon tetras, six of, Guppies, five of and some small algae-eating catfish like Otocinclus

If you want to go off-piste then a community of true nano species such as Boraras, Danio margaritatus or Danio erythromicron would be wonderful. There are even tiny Corydoras catfish species like Corydoras hastatus or pygmaeus, and tiny Sparkling gourami. With a mature tank, good water quality and regular maintenance you could keep a community of 20 tiny nano fish in a 30 litre BiOrb, or 15 fish the size of a Zebra danio. 

BiOrb Classic 60 litre

At nearly 20”/50cm diameter and 60 litre volume, the BiOrb Classic LED and MCR models hold as much water as the average two-foot tank, so could hold a comparable range and quantity of fish. For temperate you could mix White Clouds, Danios, Variatus platies and either a pair of Paradise fish or Florida flagfish.

Go tropical and you could keep groups of many of the most popular fish including tetras, rasboras, small barbs like Cherry barbs, guppies and platies. For a stand out specimen fish once the tank is mature how about a male Dwarf gourami or a Blue ram? Aim for a total of 20-25 fish built up over time, and don’t add anything which grows to over 5cm body length. 

BiOrb Classic 105

At 24”/60cm diameter and 28 gallons or 105 litres of water, the BiOrb Classic 105 not only looks big, it holds as much water as an average three-foot tank! We’ve left goldfish out of our BiOrb stocking recommendations until now as they grow large, but we feel that a few small fancy goldfish like Black telescopes in a 105 litre aquarium is ok until they grow, and it will add to your Feng Shui!

Leave the goldfish out and you could build quite the coldwater community including White Clouds, Danios, and Variatus platies, but this time you could also include Peppered corydoras and Rosy barbs. This would be a colourful, active tank filled with easy to keep, hardy fish, and you don’t need a heater. Mature the tank over weeks and months you could house up to 30 adults of a mix of the above, in total.

For tropical fish, you could add some larger tetras like Serpae, Black widows or Xray, a pair of Dwarf gourami or Honey gourami and a visually striking group of Harlequin rasboras or Pentazona barbs. At 25”/62cm in height you could select fish to occupy the top, middle and bottom layers of the tank.

Guppies, Gourami and danios will swim at the top, tetras and rasboras in the middle, and Rams, Corydoras and Cherry barbs will stay close to the bottom. Colour and activity at every level, and up to 30 small tropical fish. 

Got a different BiOrb model like a Cube, Flow, Halo, Life or Tube? Stick to the same volume and fish stocking recommendations as the BiOrb Classic 15, 30 and 60 litre models listed above.