Consider the size of your tank before choosing fish. Smaller tanks are suitable for nano fish species, while larger tanks can accommodate a variety of sizes and species.
Different fish species exhibit varying temperaments. Some are peaceful, while others can be aggressive.
Understand the water requirements of your chosen fish species. Some need specific water conditions like pH levels, temperature, and hardness to thrive.
Check the compatibility of fish species you plan to keep together. Some species have natural partnerships, while others may be territorial or prone to aggression.
Consider your experience level as an aquarist. Some fish are hardy and low-maintenance, while others require specific care and attention.