Pond Boss Forums FISH & FISHING Sunfish-Including Largemouth and Smallmouth Bass LMB Markings

Several good informative responses here, but let me add an observation I've made on a LMB I have in an aquarium in the house.

I caught the guy out of one of our ponds last summer and have had him in a tank for about a year now. He has grown about 5 inches in that time and seems to be healthy. I maintain the water pretty actively and it is always nice and clear and he gets light for about 10 hours per day.

What I have seen is that his coloration - including his black stripe - changes multiple times throughout the day pretty much daily. Depending on mood, feeding status, time of day, and, I'm sure, other factors that I am unaware of, his colors change along with his physical posture. By posture, I mean that there are times both sets of his "back fins" are standing up versus times that only the long dorsal fin is up. Same with the little fins below his pectoral fins. His stripe and the spots above his lateral line also come and go throughout the day. At some times, he has incredibly vivid color, and at others, he looks just like the guy you in your pic.

All that is to say I really have no idea why they do this, but it seems like in addition to things like turbidity and light penetration, there may also be some physiological factors that influence a LMB's outward appearance. It may be nothing to worry about if the water conditions are good - it may just be that he's kind of pissed that he fell for the whole artificial lure thing and is feeling sheepish!