Fish all the sudden started to hide

[Quetzal.n]

I have a majestic angel, a goldflake angel, two spotbreast angels and a double whiptail. I've had them for 4 months now and they've been very active and healthy. They're all around 2.5-3" rn. About a week ago some of them started hiding under rock. First the majestic, then the double whiptail, and today I found my goldflake hiding too. They'll still come out and eat when they see me but this never happened before.
The only thing i could think of is that I added some hermit crabs into the tank a couple weeks ago. Could this be caused by parasites/diseases brought in with the hermit crabs?

 

[Pbh-reef]

Hmmm hiding could be a sign of aggression or of disease. Velvet and flukes come to mind as possible culprits if it is a disease. Look for head twitching and scratching. I hope it’s nothing for your sake.

 

[Pbh-reef]

another possibility is internal parasites making the fish tired

 

[DeniseAndy]

Man, I hate when this happens with fish. 4 months you think all is well and bam, something comes up. I hope for you and the fish it is just a fear response to new additions. Keep a close eye on them and get some meds and qt ready in case.

 

[Jaebster]

What about stray voltage in tank?

 

[shred5]

I have seen stray voltage cause this.

 

[DeniseAndy]

I always forget about that one. I have always had ground probes and never worried. I have had heaters burn out and break, with no issues. Check for that first. Heaters are usually the culprits.

 

[Peace River]

Hiding can be caused by many things that cause stress including the vibration from pumps or activities happening around the tank (in addition to the issues mentioned above).