When choosing glass glue for fish tanks, the core priority should be to ensure waterproof sealing, bonding strength and non-toxic safety. Different types of glass glue are suitable for fish tanks of different sizes and usage scenarios. The following recommendations are classified according to "regular fish tanks, large/professional fish tanks, repair scenarios", and reliable brands are also included for easy selection on demand: Small conventional fish tanks (≤1.2 meters) This type of fish tank has low water pressure, so you can choose high-quality acidic silicone glass glue. It has strong viscosity, fast curing and high cost performance, and is suitable for daily household use. We recommend German WACKER 131, Changlu acid fish tank glue, Misawa fish tank special acid glue, etc. These glues are mostly transparent and have good flexibility after curing. They can firmly bond the glass and avoid affecting the appearance of the fish tank. The surface drying time is usually 10-30 minutes, and it can be initially filled with water in about 24 hours. Be careful to avoid ordinary neutral glass glue, which has low viscosity and can even be lifted up with your fingernails after curing, which can easily lead to water leakage.  Medium and large fish tanks (>1.2 meters) Medium and large fish tanks have high water pressure and require high structural stability and durability of glue. Aquarium-specific glue or structural glue is preferred. Aquarium-specific glues are highly targeted, such as WACKER 121, which is an acidic silicone glue specially designed for large fish tanks. It is highly waterproof and non-toxic, and is suitable for fish tanks above 1.5 meters. Structural glue (such as 995 structural glue) was originally used in glass curtain walls and other projects. It has outstanding waterproofing, high and low temperature resistance, and anti-aging capabilities. It cures quickly and has super viscosity, and has a service life of up to 10 years. Years and above, suitable for very large fish tanks or commercial aquariums, and can cope with long-term high-pressure water environments.  Fish tank repair scene: To repair local cracks and water leaks, you need to choose a special glue adapted to “quick curing” or “underwater construction”. For example, WACKER's acid glass glue has quick-drying properties and is suitable for ordinary crack repairs. It is easy to operate and is not prone to secondary cracking after bonding. If you need to use water to repair leaks, you can choose underwater bonding sealants from brands such as Odetron and Guanguda, which can be applied directly in the water to quickly plug leaks and avoid fish and shrimp stress caused by emptying the fish tank.  In addition, there are some brands with excellent reputations that you can directly refer to, such as domestic silicon treasure, Baiyun, and Zhijiang. Their special glue for fish tanks is environmentally friendly, non-toxic, has high tensile strength, and is suitable for household and small commercial fish tanks. The imported Dow Corning glass glue has excellent weather resistance, good colloid elasticity, and can buffer external impacts, making it suitable for scenes that require high stability.