Betta fish typically show the following classic signs when approaching death, and a comprehensive judgment should be made based on changes in their behavior, body posture, and physiology:
1. Abnormal Behavior
Sudden Drop in Activity Level
The fish stays at the bottom of the tank or floats on the water surface for long periods, responds sluggishly to stimuli, and may even exhibit abnormal postures such as rolling onto its side or twitching.
It loses balance while swimming, and may be seen “standing upright” or spinning in circles.
Abnormal Breathing
The frequency of gill cover movements increases significantly (normal rate is approximately 15–20 times per minute), or the fish experiences pauses in breathing.
2. Changes in Body Surface and Physiology
Faded Body Color
The body color fades quickly or turns pale; in severe cases, it takes on an “ashen white” appearance, and peeling of the skin mucosa may occur.
Abdominal Abnormalities
The abdomen becomes distended due to dropsy, with scales standing upright (a condition known as pineconing), and the abdomen feels inelastic when pressed.
Fin Damage
The caudal fin and dorsal fin show signs of rot, calcification, or breakage; in severe cases, the fins cannot spread normally.
3. Other Warning Signs
Loss of Appetite: The fish refuses food for more than 2 consecutive days, or has difficulty swallowing.
Abnormal Excretion: Defecation decreases or stops entirely, and the feces appear as white mucus.
4. Emergency Handling Recommendations
Isolation and Observation
Immediately transfer the sick fish to a separate container to prevent cross-infection.
Water Quality Regulation
Replace 1/3 of the water, raise the temperature to 28°C (do not increase the temperature by more than 1°C per day), and add coarse salt to achieve a 0.3% concentration.
Medication Treatment
For bacterial infections: Use a bath with yellow powder (potassium permanganate) or methylene blue.
For parasitic infestations: Use a low-concentration bath with trichlorfon.
Note: If the fish shows “death throes” (such as repeated rolling or darting around), it usually indicates organ failure, and the cure rate is extremely low.