Glass vs Acrylic Fish Tank: The Differences You Need to Know

Glass fish tanks and acrylic fish tanks differ in weight, scratch resistance, optical clarity, cost, and customization options. Glass aquariums cost less and resist scratches better, while acrylic aquariums weigh roughly half as much and offer unlimited custom shapes. Once you’ve committed to a material and started your project, switching isn’t practical — so understanding these differences upfront saves time and money.

A Brief History of Aquarium Materials

British naturalist Philip Henry Gosse coined the term “aquarium” in the 1800s, combining the Latin aqua (water) and arium (a place for relating to). Early aquariums were constructed with a slate bottom, with an open flame heating the slate to keep the water warm. Glass panels were sealed in place with waterproof putty.

All-glass aquarium construction emerged as silicone sealer replaced putty, bonding glass bottom and side panels together with plastic frames for structural support. Nearly all aquariums were built in rectangular or cube shapes, with hexagon tanks arriving later.

The Birth of Acrylic Aquariums

A thermoplastic known as “acrylic glass” — formally called Poly(methyl methacrylate) and sold under brand names like Plexiglas, Lucite, and Perspex — eventually found its way into aquarium construction. Acrylic should not be confused with polycarbonate, a similar clear plastic. Polycarbonate has high impact strength but contains harmful bisphenol-A (BPA) and is not suitable for aquarium use.

Early acrylic aquariums generated excitement because panels were bonded with a solvent that effectively welded the pieces together, leaving no visible silicone-sealed seams. Acrylic was also used to create the first bowfront aquariums, curving the front panel instead of the standard flat glass design.

Glass Fish Tanks

Glass remains the most popular material for standard aquariums due to its scratch resistance and optical clarity. From small desktop setups to large aquarium systems, glass tanks dominate the market at every size. A standard 55-gallon glass aquarium weighs approximately 78 pounds empty, and glass tanks generally cost 40–60% less than comparable acrylic models.

Modern Glass Technology

Bent glass aquariums start as flat glass sheets heated above 1,000°F until pliable, then shaped over curved molds. This process creates seamless curves and eliminates corner seams. Bent glass is stronger than flat glass, which means the panels can be thinner and lighter than traditional flat glass aquariums.

Low-iron glass (such as Starphire®) contains less than one-tenth the iron content of regular glass. Standard glass develops a noticeable green tint along the edges as thickness increases, which distorts the color and clarity of the aquarium. Low-iron glass eliminates this green cast and produces a distinct azure-blue edge instead. Premium planted tanks, reef aquariums, and public aquariums routinely use low-iron glass for maximum visibility and true color rendering.

Rimless glass aquariums eliminate the black or wood-grain plastic frame found on traditional tanks. The result is a clean, elegant appearance — rimless tanks truly look like a glass jewel. Many modern rimless aquariums combine low-iron glass with frameless construction for the ultimate viewing experience.

Tempered glass is stronger than regular glass and is sometimes used for aquarium bottom panels. However, tempered glass cannot be drilled — it will shatter if you attempt it. Always verify whether your tank uses tempered glass before drilling for custom plumbing.

Acrylic Fish Tanks

Acrylic aquariums offer unique advantages for custom builds and large installations where weight and impact resistance matter most. Acrylic weighs roughly 50% less than glass at equivalent dimensions, and acrylic is approximately 17 times more impact-resistant than glass — making it far less likely to crack from accidental bumps.

Modern Acrylic Technology

Today’s acrylic formulations include UV inhibitors that prevent the cracking and brittleness associated with older acrylic products. Modern acrylic is used to make aquariums ranging from inexpensive, tiny pico desktop tanks to large custom-fabricated systems.

Nearly all low-cost desktop aquariums are made from acrylic because they are lightweight, easy to ship, and less fragile than glass. Custom aquarium manufacturers also favor acrylic because it is easy to cut, shape, and glue together — and the finished product is easier to carry into the room where it will be set up.

Acrylic Beyond the Main Tank

Acrylic is widely used for aquarium accessories and filtration equipment, not just the main display tank. Sumps, protein skimmers, and refugiums are commonly manufactured from acrylic because of its light weight and ease of fabrication. In-tank filters often use acrylic dividers and media trays that don’t add significant weight to the aquarium.

Side-by-Side Comparison

Which Should You Choose?

There is no universal winner between glass and acrylic fish tanks — the best choice depends on your specific setup, budget, and priorities.

Choose a glass aquarium if:

• You want a standard-sized tank at a reasonable price
• Scratch resistance is a priority (especially with active fish or children)
• You prefer the clearest possible viewing, particularly with low-iron glass
• Weight is not a limiting factor for your location
• You’re setting up a beginner tank or mid-size community aquarium

Choose an acrylic aquarium if:

• You need a custom shape, size, or configuration
• Weight is a limiting factor (upper floors, moveable setups, or large aquariums)
• Impact resistance matters (households with children, high-traffic areas)
• You want invisible seams for a seamless look
• You’re comparing bowfront vs flat designs and want a curved front panel

Conclusion

Both glass and acrylic make excellent aquariums when matched to the right application. Glass offers unbeatable scratch resistance and clarity at lower prices, making it the standard choice for most fishkeepers. Acrylic provides lightweight construction and unlimited customization for those willing to invest more and maintain it carefully.

The debate between glass and acrylic aquariums has lost much of its intensity as both materials have improved dramatically. Modern low-iron glass rivals acrylic for visual appeal, while modern acrylic with UV inhibitors has eliminated the yellowing concerns of the past. Consider your budget, space constraints, tank size, and long-term maintenance preferences when making your decision.