Betta Tail and Fin Types, Explained — and Why a Plakat Is Still a Halfmoon
If you have ever bought a betta advertised as a “halfmoon” and been disappointed by a fish with a short, rounded tail, you were not sold the wrong fish. You were sold a halfmoon plakat, and nobody explained the difference.
Betta fin and tail types are named after the shape of the tail and the length of the fins. Two words get used together, and understanding how they combine is the whole trick.
The Two Parts of Every Type Name
Every type name is built the same way: a tail shape plus a fin length.
Tail shape describes the trailing edge
- Halfmoon — the tail forms a half circle, 180 degrees or more
- Delta — the tail is a triangle, closed and straight-edged
- Veiltail — a single long trailing fin, no split
- Crowntail — the tail rays extend past the membrane, like a crown
Fin length describes how far the fins reach
- Plakat — short, rounded, held close to the body
- Ocho — medium length, floating rather than dragging
- Long fin — the full flowing fin
So What Is an HMPK?
Put the two together. HMPK means Halfmoon Plakat: the tail is halfmoon-shaped, but the fins are short and rounded rather than long.
So a plakat is a halfmoon in tail shape. What it is not is a halfmoon longfin — which is the fish most people picture when they hear “halfmoon.”
The distinction matters in the shop, because the two need different tanks. Long-finned bettas are usually better suited to a larger tank with still water. A short-finned plakat is more comfortable in a smaller one. A tank that suits one is not automatically right for the other.
The Types You Will Meet in the Shop
- Halfmoon plakat (HMPK) — half-circle tail, short rounded fins
- Halfmoon — half-circle tail, long flowing fins
- Delta — triangular tail
- Crowntail — spiky tail rays
- Veiltail — single trailing fin
What to Ask Before You Buy
- Ask for a video of the actual fish, not a stock photograph. Every betta we sell is filmed on the animal itself, so you can see the fin length and the tail edge before you pay.
- If fin length matters to you, say so. The word “halfmoon” on its own does not tell you whether you are getting long or short fins.
- Match the fish to the tank. Short-finned and long-finned bettas are not equally comfortable in the same space. A betta needs at least 20 litres, 30 litres is the sweet spot, and 30 litres or more if you are planting.
Why a Young Betta May Look Different From Its Photo
Young bettas change as they mature, and the change can be significant. Our guide to why young bettas change colour explains what to expect, and what is worth worrying about.
