A Bridge for Your Fish Tank? We Look at the Pros and Cons

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If you have two small fish tanks, but you want more fish than just one tank can comfortably hold, why not construct a bridge between the two tanks?

That increases the total water volume available, giving you the scope to increase your stock without overcrowding.

In addition, cleaning the tanks is made easier because all you need to do is move the fish into the other aquarium and close off the bridge while you work.

Keep reading to learn the pros and cons of an aquarium bridge and to find out how to build one of these intriguing items.

What Is a Water Bridge?

A water bridge is essentially a simple tunnel that you use to connect two fish tanks from above.

The bridge comes from the top of one tank before going into the other, leaving the ends submerged in water in separate tanks. When the bridge is set up correctly, water flows through the tunnel, allowing your fish to cross from one tank to the other.

What Are the Benefits of Building a Water Bridge for Your Fish?

There are a few benefits to creating a water bridge for your fishy friends.

  • Creates more space for your fish
  • Makes tank cleaning easier
  • Provides habitat enrichment for your fish

If you have curious fish, such as a betta, you could even create two totally different environments in each tank. That way, your fish can enjoy a change of scenery wherever they want to.

However, if you’re planning on allowing your fish access to two different environments, you must ensure that all the fish get along well together. Basically, if your fish wouldn’t be okay in a community tank, you can’t connect them via a water bridge.

In addition, there must be sufficient overall space to accommodate the numbers of fish you have.

What Do You Need to Make a Water Bridge for Your Fish?

You can build a water bridge out of several different materials.

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Glass is probably the most popular choice since it’s safe for your fish and is generally what the fish tanks themselves are made of.


I think that matching the bridge materials to those of the tank is preferable, as that creates a more pleasing aesthetic. However, that’s entirely down to personal choice.

If you’re building your bridge from glass, you need a handheld glass cutter so that you can cut the glass into the size and shape of the tunnel you want. The separate pieces of glass are connected with watertight silicone.

When designing and cutting your bridge, make sure that it’s large enough to comfortably accommodate your fish.

Easier Option

If you’re not confident with cutting glass, you might prefer to use PVC for the water bridge, using pipes and elbow connectors. That way, cutting, measurement, and assembly will be easier.

In addition, clear pipes allow you to watch your fish swimming through the bridge, and you can monitor the water flow to ensure that some air bubbles are present to break the vacuum.

Establishing Flow

Obviously, you need water to flow from one tank to the other through the bridge. To do that, you need to use a flexible length of tubing to siphon air out of the tunnel, pulling the water through.

So, when you remove the air from the bridge, you create a vacuum that keeps the water inside.

Important note:

Keeping a constant flow through the water bridge is essential for your fish’s health. If the water inside the bridge becomes stagnant, oxygen levels will not be sufficient to sustain life, and any fish inside the bridge will die.

Will My Fish Use the Bridge?

One thing you can’t be sure of is whether your fish will even use the bridge once you’ve gone to the trouble of building it for them.

I know a guy who had his water bridge professionally constructed and fitted to his tank, only to find that his angelfish completely ignored it! However, in this Youtube video, a curious betta fish seems to love the water bridge his owner created for him.

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So, whether the fish use the bridge or not seems to depend on the fish species you have and the individual’s personality.


Here are the answers to a few commonly asked questions about water bridges for fish.

Q: Is a Bridge a Good Way of Creating More Space by Using 2 Smaller Tanks?

A: Yes, constructing a water bridge can be a very effective way of increasing the overall volume and capacity of your fish accommodation.

Q: Does a Betta Fish Like the Idea of Having a Split Territory to Patrol?

A: Betta fish are highly territorial, intelligent creatures, and the idea of having two territories to patrol and guard seems to appeal to them.

In the wild, these fish are accustomed to having a large territory of up to 3 sqft to look after, so the more space your betta has to call his own, the better.

Q: Would a Betta Find the Idea of Two Tanks With a Bridge Stressful?

A: It’s unlikely that your betta fish would find an extended territory connected by a water bridge stressful. In fact, keeping fish of any species in a tank that’s too small is far more stressful than offering them more space.

From what we found when researching the subject of water bridges, many fish simply ignore the bridge. More curious individuals seem to enjoy the experience of traveling from one environment to another, much as they would in the natural environment.

Q: Cons of Water Bridges

A: The main downside of water bridges is that not all fish use them. So, you could go through the time and trouble of building and fitting a bridge to your tanks, only to discover that your fish ignore it!

Q: Are Water Bridges a Useful “Toy” for Your Fish or a Harmful Idea Purely To Entertain Humans?

A: That’s an interesting question of ethics. Watching your fish traveling from one tank to another through a bridge is undoubtedly entertaining for the onlooker, and many fish seem to enjoy the experience of relocating whenever they want to.

You can’t force your fish to make the journey; it’s entirely down to the fish to make that decision. So, we don’t think that using water bridges is harmful or detrimental to your fish.

Of course, you must ensure that the bridge is large enough to comfortably and safely accommodate your fish.

Final Thoughts

Did you enjoy our guide to whether a water bridge linking two tanks together is a good idea for your fish? If you did, please take a moment to share the article.

Water bridges can be a good way of linking two fish tanks together to create a more spacious environment for your fishy friends. Of course, there’s no guarantee that your fish will decide to use the fish tank bridge; that seems to depend on the species and the temperament of the individual fish.

Do you have a water bridge for your fish? Do they love it or ignore it, and is it a popular option among your fellow aquarists? Tell us in the comments box below.

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