Midas Blenny Not Eating or Hiding
A Midas Blenny that is hiding or refusing food is most commonly a newly introduced fish still acclimating. In an established fish, a sudden change in behavior warrants investigation. This guide covers how to tell the difference and what to do.
Normal Behavior: New Fish Acclimation
Newly introduced Midas Blennies commonly hide for several days while acclimating to a new tank. During this period the fish may:
- Stay tucked into rockwork for most of the day
- Refuse food or eat very little
- Only emerge briefly when the tank is undisturbed
This is normal. Most Midas Blennies begin perching visibly and accepting food within one to two weeks of introduction. The species is naturally bold once settled — a fish that remains persistently hidden beyond two weeks warrants a closer look.
When to Be Concerned
Investigate further if:
- An established fish that was previously active and eating well suddenly stops
- The fish has been in the tank more than two weeks and still refuses all food
- You observe rapid breathing, clamped fins, unusual coloration changes beyond normal mood shifts, or visible lesions
- The fish appears thin or visibly deteriorating
Troubleshooting Steps
1. Check Water Parameters
Test for ammonia, nitrite, nitrate, pH, salinity, and temperature. Parameter issues are the most common cause of sudden behavioral changes in reef fish. Address any problems before anything else.
2. Check for Tankmate Aggression
Observe the tank during feeding. Another blenny or similarly shaped fish may be harassing the Midas Blenny and preventing it from emerging. Midas Blennies can also be the aggressor — check whether the hiding fish is being chased or is itself causing stress to others.
→ Midas Blenny Tankmates Guide
3. Try Target Feeding
Use a pipette or turkey baster to deliver frozen mysis directly near the blenny's preferred perch when the tank is calm. Feed the rest of the tank first to occupy other fish. Midas Blennies are active feeders once settled — if the fish responds to target feeding, competition at feeding time may be the issue.
4. Check for Color Change
Midas Blennies can shift from golden-yellow to blue-purple when stressed. If the fish has changed color and is hiding, stress is likely the cause — identify and address the stressor rather than treating the color change itself.
5. Look for Signs of Disease
Inspect the fish when it does emerge. White spots, unusual patches, frayed fins, or labored breathing may indicate ich, velvet, or another disease requiring treatment. Quarantine and treat if disease is suspected.