Hexagon Octagon Fish Tank – The Ultimate Guide To Vertical Aquascaping

If you are looking to break away from the traditional rectangular aquarium, you are in the right place. Standard tanks are great, but they often lack the “wow factor” that a unique geometric shape provides.

When you walk into a room, nothing catches the eye quite like a hexagon octagon fish tank. These vertical wonders act as living pieces of art, offering a 360-degree view of your aquatic world.

Setting up a multi-sided tank might feel a bit intimidating at first because of the height. Don’t worry—this setup is perfect for beginners and seasoned pros alike if you know a few insider tricks!

In this guide, I will walk you through everything you need to know. We will cover stocking, equipment, and how to master the vertical water column for a thriving ecosystem.

Selecting the Perfect hexagon octagon fish tank for Your Home

Choosing between a six-sided (hexagon) or eight-sided (octagon) shape is mostly about your personal aesthetic preference. Both offer a much smaller footprint than a standard 20-gallon long tank.

A hexagon octagon fish tank is ideal for tight corners or as a centerpiece on a kitchen island. Because they are taller than they are wide, they utilize vertical space efficiently.

Before you buy, consider the material. An acrylic seam is often clearer and stronger for these shapes, though glass remains a classic choice for scratch resistance.

Hexagon vs. Octagon: The Structural Differences

Hexagon tanks have 6 panels, creating wider viewing angles on each side. They are more common in local fish stores and often come in complete kits.

Octagon tanks have 8 panels, making them appear almost circular from a distance. These are rarer and often provide an even more panoramic view of your fish.

Regardless of the side count, both require a sturdy foundation designed specifically for their unique weight distribution.

The Importance of Height and Depth

The defining feature of a hexagon octagon fish tank is the depth. While a standard tank focuses on horizontal swimming space, these focus on height.

This verticality allows you to keep species that enjoy different levels of the tank. You can have bottom-dwellers, mid-water schoolers, and top-level dwellers all in one column.

However, remember that deeper water means you need stronger lighting to reach the plants at the bottom. We will dive deeper into lighting requirements later in this guide.

The Vertical Advantage: Why Go Geometric?

The most significant benefit is the space-saving nature of these builds. You get a high volume of water without taking up an entire wall in your living room.

Beyond space, the 360-degree viewing is a game-changer. You can observe your Betta splendens or shrimp from almost any angle without the “blind spots” of rectangular corners.

It also allows for unique aquascaping opportunities. You can use tall driftwood or “tree-style” escapes that would never fit in a shallow breeder tank.

Creating a Living Column of Color

In a vertical tank, the “layering” of fish becomes much more apparent. It is a beautiful sight to see a school of tetras hovering in the middle while corydoras scavenge below.

This setup mimics deep-water environments found in nature. Many fish feel more secure with a tall vertical water column where they can retreat upward or downward.

If you are setting up your first multi-sided aquarium, you’ll quickly realize how much fun it is to decorate vertically.

Aesthetic Versatility

Whether your home decor is modern or traditional, a hexagon octagon fish tank fits right in. They often look like high-end pillars of light once the LEDs are on.

Many hobbyists use them for “theme” tanks. Think of a sunken city or a towering kelp forest—these shapes lend themselves to vertical storytelling.

Overcoming the Challenges of Vertical Tanks

While beautiful, these tanks do present some unique hurdles. The most notable is the surface area to volume ratio, which affects oxygen levels.

Because the top opening is smaller than a rectangular tank, there is less room for gaseous exchange at the surface. This can lead to lower oxygen levels if not managed.

Don’t let this discourage you! A simple air stone or a well-placed internal powerhead will keep the water moving and oxygenated for your fish.

Managing Gas Exchange

To ensure your fish stay healthy, you must break the surface tension of the water. This allows carbon dioxide to escape and oxygen to enter.

Using a filter with a spray bar or a bubbler is a great solution. If you notice your fish gasping at the surface, it’s a sign you need more circulation.

Regular water changes are also vital. In a tall tank, debris can settle in “dead zones” where water flow is weak, so keep an eye on those corners.

Maintenance and Reach

Let’s be honest: cleaning a tall tank can be a bit of a workout for your arms. If you have a 30-gallon hex, reaching the bottom substrate can be tricky.

I highly recommend investing in long-handled algae scrapers and extra-long planting tweezers. These tools make life so much easier when you’re working in a deep tank.

You might also find vertical water column challenges like temperature stratification, where the bottom is colder than the top.

Best Fish for a hexagon octagon fish tank

Not all fish are suited for vertical living. Fast-swimming, horizontal sprinters like Giant Danios might feel cramped in a hexagon shape.

Instead, look for fish that “hover” or move gracefully up and down. The Pterophyllum scalare (Angelfish) is the absolute king of the hexagon tank.

Their flat, tall bodies are perfectly designed for navigating vertical spaces. A pair of Angelfish in a 30-gallon or larger hex is a classic, stunning choice.

Top Stocking Choices

• Angelfish (Pterophyllum scalare): Perfect for the height and elegance of these tanks.
• Gouramis: These labyrinth fish enjoy the stiller waters near the top.
• Discus: For advanced keepers, a large octagon tank provides the depth these “pancakes” love.
• Bettas: A single Betta splendens thrives in smaller 5–10 gallon hex tanks with low flow.
• Schooling Tetras: Species like Rummy Nose or Cardinal Tetras look amazing as they tight-school in the middle.

Invertebrates and Bottom Dwellers

Don’t forget the cleanup crew! Cherry shrimp and Amano shrimp love climbing up tall plants and driftwood to graze on algae.

For the bottom, consider small loaches or Corydoras. Just ensure you provide plenty of “landing pads” like flat rocks or broad leaves for them to rest on.

Since the floor space is limited, avoid overstocking the bottom. One or two species of scavengers are usually plenty for a standard hexagon octagon fish tank.

Essential Equipment for Your Setup

Your equipment choices will make or break your success. Because of the depth, standard “kit” lights often aren’t enough for live plants.

You will need a strong LED light that can penetrate 20+ inches of water. Look for lights with a high PAR rating if you plan on growing a lush carpet.

Heating is another factor. Use a reliable submersible heater and place it near the filter intake to ensure the warm water is distributed evenly.

Filtration Strategies

A hexagon octagon fish tank can be filtered in several ways. Many older models use an undergravel filter, which is great for biological filtration but harder to clean.

Modern setups usually benefit from a HOB (Hang-On-Back) filter or a canister filter. If your tank is very tall, a canister filter is best for reaching the bottom.

An internal powerhead can also be added near the bottom to prevent “dead spots” where waste might accumulate and rot.

Substrate and Planting

Choose a substrate that supports plant growth but isn’t too light. In a tall tank, you want your plants to stay firmly rooted.

Since you’ll be reaching down deep, a nutrient-rich soil capped with gravel or sand works wonders. It provides the stability needed for tall, reaching plants.

| Feature | Hexagon Tank | Octagon Tank | | :— | :— | :— | | Viewing Angles | 6 distinct panels | 8 panels (near-circular) | | Footprint | Very Compact | Compact to Medium | | Best Fish | Angelfish, Tetras | Discus, Gouramis | | Difficulty | Beginner-Friendly | Intermediate | | Flow Needs | Moderate | Moderate to High |

Aquascaping the Vertical Masterpiece

The key to a beautiful hexagon octagon fish tank is “The Rule of Thirds,” but applied vertically. You want visual interest at the bottom, middle, and top.

Start with a tall piece of spider wood or manzanita driftwood as your centerpiece. This creates a “skeleton” for your plants to climb toward the light.

Use “epiphyte” plants like Anubias or Java Fern. You can wedge these into the nooks of your driftwood at various heights for a natural look.

Choosing the Right Plants

You need plants that can grow tall and handle lower light levels at their base. Vallisneria spiralis is a fantastic choice for these tanks.

It grows in long, ribbon-like strands that will reach the surface and trail across the top, providing shade and security for your fish.

Other great options include Amazon Swords and tall Cryptocoryne species. These create a dense jungle look that fills the vertical space beautifully.

Lighting for Deep Water

As mentioned, light loses intensity as it travels through water. If your tank is over 18 inches deep, standard lights won’t reach the bottom.

Consider upgrading to a high-output LED. This ensures your ground-cover plants get enough energy to photosynthesize and stay green.

If you find your bottom plants are turning yellow, you might need to stick to low-light plants like mosses or Java Fern for the lower third of the tank.

Maintenance Routine for Multi-Sided Tanks

Maintaining a hexagon octagon fish tank isn’t harder; it’s just different. You need to be more mindful of the corners where algae likes to hide.

I recommend a weekly 20-25% water change. This keeps the nitrates low and ensures the water remains crystal clear for that 360-degree view.

When vacuuming the gravel, be thorough. Because the floor space is smaller, waste can build up quickly if you miss a spot.

Algae Control

Algae can be more visible on the multiple panels of a hex or octagon tank. A magnetic glass cleaner is your best friend here.

Clean the glass every few days to prevent stubborn green spot algae from taking hold. It’s much easier to do a quick wipe than a heavy scrub later.

Also, keep your lighting on a timer. 8–10 hours of light is usually the sweet spot for preventing algae blooms while keeping plants happy.

Water Parameter Stability

Because these tanks are often smaller in volume compared to long tanks, parameters can shift faster. Invest in a good liquid test kit.

Check your Ammonia, Nitrite, and Nitrate levels regularly. This is especially important during the first few months of a new setup.

If you stay on top of your water changes, your hexagon octagon fish tank will remain a healthy, thriving environment for years to come.

FAQ: Common Questions About Multi-Sided Tanks

Q: Are hexagon tanks harder to keep than rectangular ones? A: Not necessarily! They just require specific equipment (tall tools) and a bit more attention to water circulation due to the smaller surface area.

Q: Can I keep goldfish in a hexagon tank?
A: It depends on the size. Fancy goldfish can work in larger hex tanks, but common goldfish need much more horizontal swimming space and are better off in long tanks.

Q: How do I choose a lid for my octagon tank?
A: Finding a replacement lid for a hexagon octagon fish tank can be tough. Most come with custom hoods. If yours breaks, you may need to order a custom acrylic or glass top.

Q: Do these tanks leak more often?
A: As long as the tank is level and on a proper stand, they are very reliable. The multiple seams are reinforced during manufacturing to handle the vertical pressure.

Conclusion: Embracing the Geometric Beauty

Investing in a hexagon octagon fish tank is a rewarding journey that adds a unique flair to your home. It challenges you to think differently about space and design.

By focusing on vertical aquascaping, choosing the right “tall” fish, and ensuring proper oxygenation, you can create a stunning aquatic pillar.

Remember to take it slow, pick a sturdy stand, and enjoy the incredible 360-degree views of your underwater world. Happy fish keeping!