Ruby Sharks: The Good, The Bad, and The Beautiful

The Ruby Shark (also known as the Rainbow Shark or Red-finned Shark) is well-known among fishkeepers for being extremely territorial, especially towards other Sharks.

In an aquarium, these colourful freshwater fish will claim specific areas as their own—such as caves, pieces of driftwood, or particular corners of the tank—and defend them aggressively.

Whilst they can usually get along with different types of fish (particularly those that swim at different levels in the tank), Ruby Sharks show serious aggression towards their own kind, which is why they are best kept singularly. They will chase, nip fins, and display threatening behaviour that can cause major stress or even injury to weaker Sharks.

This aggression becomes even worse in smaller tanks where fish have nowhere to escape. It's nearly impossible to keep multiple Ruby Sharks together unless you have a very large aquarium with plenty of hiding places and decorations to block their view of each other.

Even in ideal conditions, the dominant Ruby Shark will constantly patrol its territory, making sure any other Ruby Shark knows to stay away. This territorial behaviour comes from their wild habitat in the fast-flowing streams of Southeast Asia, where competition for the best feeding spots and shelter would be intense.

Despite their feisty nature, Ruby Sharks have many wonderful qualities that make them popular aquarium fish.

They're absolutely stunning to look at, with sleek dark grey to black bodies that contrast beautifully with their bright red or orange fins—a real eye-catching addition to any tank.

These fish are tough and easy to care for, handling different water conditions well and rarely getting sick when looked after properly, making them suitable even for fishkeepers with some experience.

Ruby Sharks are incredibly active and fun to watch as they constantly swim around their territory and display natural behaviours like eating algae, which makes them helpful members of your tank's cleaning crew.

Because they love eating algae, they help keep your rocks, decorations, and glass clean, reducing how much maintenance you need to do whilst following their natural instincts.

Their confident, bold personality means they're always out and about in the tank, unlike shy fish that spend all their time hiding, giving you an energetic, interactive pet that becomes the star of your aquarium.

When kept as the only Ruby Shark in the tank with other peaceful fish and given plenty of space, they can live for 5-8 years or longer, becoming long-term companions that bring life, colour, and personality to a well-planned community tank of at least 200 litres.