Behaviour and Body Language

Betta Gillfriend care rules: one betta per tank. Mirror or flare practice: one 2-minute session a day, with at least 2 rest days a week. Train: up to 10 minutes a week.

Bettas are expressive fish. Once you know your betta's normal routine, small changes in posture, colour, breathing or appetite are often the first warning sign that something is wrong. Researchers who keep large betta colonies note that sick bettas usually show recognisable behaviour changes, most often clamped fins, lethargy, and losing interest in food.

Tip: Spend a minute or two each day just watching. Use the app's daily health check to note anything unusual. Knowing what's "normal for Rip" is the most powerful health tool you have.

Normal vs worrying at a glance

Behaviour	Usually normal	Worrying if...
Swimming	Patrols the tank, explores plants, comes to the front when you approach	Struggles to stay level, floats or sinks without control, swims in spirals, darts wildly
Resting	Short rests on leaves, plants or the bottom, especially at night or after eating	Lies on the bottom most of the day, wedges into corners, hides constantly
Surface trips	Regular quick trips up for a gulp of air	Hangs at the surface gasping or "piping" (mouth at the surface constantly)
Breathing	Calm, steady gill movement	Fast or laboured breathing, gill covers held open, one gill flared more than the other
Fins	Spread open and flowing (or held neatly, in plakats), flared during displays	Clamped close to the body for long periods; ragged, shrinking or discoloured edges
Colour	Bright and consistent (marble and koi patterns can slowly change over time)	Sudden paleness, darkening, dull patches, a gold or rusty sheen, white spots or fuzz
Appetite	Eager, sometimes "begging" at the front glass	Spits food out, ignores food, or stops eating for more than a day or two
Rubbing	Very occasional brush against something	Repeatedly scratches or "flashes" against decor, gravel or the glass
Bubble nests	A sign of a comfortable male (many build often; some never do)	No concern either way on its own
Flaring	Short displays at reflections, new objects or other bettas	Flaring constantly, or never calming down (see Enrichment and flare training)

The UK Ornamental Aquatic Trade Association (OATA) gives a similar list of changes to watch for: hanging at the surface or sitting on the bottom, erratic swimming, colour changes, more hiding or aggression than usual, faster or slower gill movement, white spots or fluffy growths, loss of fins or scales, weight changes, and eating less. RSPCA Australia adds that a healthy betta is usually responsive to you, and constant hiding suggests a problem.

Sleeping and resting

Bettas have no eyelids, so they sleep with their eyes open. A resting betta is still, often a little paler, and may lie on a leaf, a plant, a decoration, or the substrate.
Many bettas like to rest close to the surface, which is why RSPCA Australia suggests tall plants with large leaves and keepers love "leaf hammocks".
Bettas need a proper night. RSPCA Australia recommends at least 8 hours of darkness, with lights on for no more than about 10 hours.
Older bettas rest more (see Old age). Long-finned males may also rest more because heavy fins are tiring.

Warning: A betta that suddenly rests most of the day, especially combined with clamped fins, poor appetite or fast breathing, is not "just sleepy". Test your water first, then check the symptom lookup table.

Bubble nests

Male bettas build floating nests of mucus-coated bubbles at the surface, often under a leaf or in a corner. In nature and in breeding, the male guards eggs in this nest (see Breeding).
Building a nest is normal behaviour that shows a male is mature and comfortable enough to spend energy on it. It doesn't mean he "needs" a female.
No nest is not a problem. Many perfectly healthy males build rarely or never. Nests also get broken up by water changes and surface movement, and that's fine.
Females occasionally blow a few bubbles too.
A research colony notes that young males start blowing nests at around 8 weeks old, and that warm water (about 28°C) suits nest building.

Flaring

When a male betta flares, he spreads all his fins, opens his gill covers so the red gill membranes stick out like a "beard", often darkens in colour, and may beat his tail sideways. It's a display aimed at a rival, his reflection, or a female.

Short bursts are normal and natural. Bettas flare at reflections, at new objects and sometimes at their owner.
Flaring takes energy. A 2013 study found that when bettas flare their gill covers, they take in less oxygen through their gills and rely more on gulping air. This is one reason long or constant flaring isn't good for them.
If your betta flares a lot at his reflection, see Enrichment and flare training for how to reduce reflections and keep flaring sessions short and positive.

Stress stripes vs breeding bars

Bettas can show stripes that look alike but mean different things:

	Stress stripes	Breeding bars
Direction	Horizontal, running from head to tail along the side	Vertical, running from back to belly, usually several light bars
Who shows them	Males and females, and very commonly juveniles and fish just bought	Females (mostly) that are ripe and ready to spawn
When	Shipping, a new tank, poor water, illness, being chased, fear	When a ripe female sees a male; often with a rounded belly and a visible white ovipositor (egg tube) just behind the ventral fins
What to do	Check water quality, reduce disturbance, give hiding places. Stripes that last more than a few days in a settled fish deserve a closer look.	Nothing, unless you plan to breed. Vertical bars on their own aren't a disease.

OATA notes that females ready to spawn show vertical bars. A vet-reviewed guide adds that not every ripe female shows them.
Many keepers report horizontal stress stripes in newly bought bettas that fade within days as the fish settles. This comes from hobby experience rather than research.
Koi, marble and dark-bodied fish can be harder to read, because their patterns hide or mimic stripes. Watch the other signs (fins, breathing, appetite) too.

Clamped fins

"Clamped" means the fins are held tightly folded against the body instead of spread out. It's one of the most useful early warning signs.

A research colony describes clamped fins as a "nonspecific symptom present in many betta illnesses". It tells you something is wrong, not what.
Common causes: poor water quality (test first), water that's too cold, a recent move, parasites such as velvet, ich or gill flukes, or bacterial infections.
Plakats hold their fins more compactly than long-finned bettas anyway. Learn your betta's normal fin posture so you can tell the difference.

What to do: test ammonia, nitrite, nitrate and temperature; correct anything that's off; look closely for spots, dust, fuzz or fin damage (a torch helps); and check the symptom lookup table. If clamping lasts more than a day or two with good water, or comes with other signs, contact an aquatic vet.

Other behaviours worth knowing

Glass surfing (swimming up and down against the glass): may mean he sees his reflection, wants out of a strong current, is bored, or doesn't like the water conditions. Check water, reduce reflections, and add plants and enrichment.
Begging at the glass: totally normal. Bettas quickly learn who feeds them. Don't let it trick you into overfeeding!
Tail biting: some bettas bite their own fins, often linked to stress, boredom or heavy fins. See Fin and tail biting.
Colour change in koi and marble bettas: the IBC notes that marble-type patterns can change over a betta's life. A koi betta like Rip may slowly gain or lose patches. Gradual change in an otherwise healthy fish is normal; sudden dulling, or a gold or white film, isn't.
Jumping: bettas jump, especially if water quality is poor or something startles them. A lid is essential.
Shimmying (shaking in place without swimming forward): OATA lists it as a possible sign of disease. Check water quality.

Sources

Care guide by Betta Gillfriend (Bespok Labs, BC, Canada). It is general information, not vet advice. If your betta is sick, ask an aquatic vet.