Question about Linear Blenny

Luky · Jun 12, 2024

This is my second Linear (Klausewitz) blenny. The first lasted many years and I never saw this behavior. My new one has started changing the color on the back half of his body from brown to white. This happens intermittently as he is swimming around. It only started after I have had him several months. He can change from normal coloration to the back half white (with some spots) in 20-30 seconds. Then be back to normal a few minutes later. There does not seem to be another fish being aggressive to him so I don't think it is a stress reaction? I have mated percs (laying eggs every 3 weeks), yellow, green, citron, engineer gobies, 3 pajama cardinals and a coral beauty. Everyone gets along and the only aggression I have seen is when a fish/Snail gets too close to the clowns eggs or my coral beauty killed a Fusilear Damsel in 24 hours after adding it (after lights out) maybe 6 weeks ago? (Not sure why? I was looking for an Anthius to add and found this unusual Damsel that I thought I would try, but it didn't work out).

Has anyone else seen this type of behavior in a Linear blenny? He seems healthy, no fin issues, eats well, swims around and perches on my corals.

Turtle_reef · Jun 13, 2024

The color changing behavior you're describing in your Linear Blenny is definitely interesting and not something commonly reported for the species. But interesting though I recently wanted one of those before I got my yellow headed jawfish but none were available so I went with the jawfish.

Some possible explanations but not entirely for sure could be stress, while you haven't observed any direct aggression towards your Blenny, there could be subtle stressors in the tank he's reacting to. This could be water quality fluctuations, competition for food or hiding spots with other fish, or even internal tank changes you might not be aware of.

communication, some fish species change color for communication purposes, like signaling dominance or attracting mates. While not as documented in Linear Blennies, it's a possibility, especially considering the mated clownfish in your tank.

Natural behavior, There's a chance this color change is a natural behavior for Linear Blennies that hasn't been widely observed yet.

Some things you could try is to keep an eye on your Blenny's overall health. Is his appetite good? Are his fins intact? Any signs of lethargy or labored breathing?
Observr any triggers ans try to see if there are any specific events that seem to trigger the color change. Does it happen at feeding time? When the lights come on or off?
Double-check your water parameters (ammonia, nitrite, nitrate, pH) to ensure they're within the ideal range for Linear Blennies.
Also could look for information on Linear Blenny behavior in online forums or scientific papers. You might find similar anecdotal reports from other aquarists. Hope this helps and hopefully it's normal behavior just no one was aware of it!

Luky · Jun 13, 2024

All my water parameters are in line for a reef tank. Been set up since 2015, using live rocks/coral from previous tank that was over 10 years old when it cracked. Fish seems perfectly healthy and no one is bullying him. I saw him white earlier just before I fed... maybe it is because he is hungry lol?