The betta and the opaline gourami are related to each other and have a lot in common. Both are great beginner aquarium fish. However, they do have some variations in temperament and care requirements, so it is is important to understand the differences between them.
The most obvious difference between the betta and the gourami is their appearance. While both species come in a number of varieties, bettas come in a much wider range of colors and patterns, including black, white and everything in between. Opaline gouramis are typically silvery blue to dark blue. Additionally, opaline gouramis are about twice as large as most bettas at 6 inches in length.
Another big difference is the prescribed size of the tank. A betta can get along in a well-maintained 1-gallon bowl. An opaline gourami requires an actual aquarium of at least 20 gallons due to its larger size. However, there's no reason a betta can't be kept in a real fish tank as well. Additionally, both species usually get along with other fish of different species. However, males gouramis and male bettas can be very violent with each other. Don't keep more than one male of either fish.
One of the big commonalities of these fish is that they both posses a labyrinth organ. The labyrinth organ is a modification of the gills that allows them to breathe air. Both bettas and gouramis live in stagnant pools of water in the wild. This special organ allows them to breath atmospheric oxygen to supplement the oxygen in the water.
Another interesting similarity between these fish is the way they proliferate the species. Both bettas and opaline gouramis construct "bubble-nests" to breed. In this type of breeding, the male prepares a nest out of bubbles and vegetation. When the eggs are laid, the male scoops them up in his mouth and spits them into the nest. The process is very similar in these two different fish.
- Ryan McVay/Stockbyte/Getty Images