My Mono's are changing color...

[jdamian13]

I have 2 Mono's (about 6") and I purchased 2 more today (4"ers)
I have noticed the my two old ones have lost alot of their black coloration and are light green looking, unlike my 2 new ones, they have very dark black coloration. Now! as I'm writing this I'm noticing that the 2 older ones are showing their black coloration more!!! Im confused....
What's the deal w/their black coloration?...

 

[bOOsteN aUdI]

pictures?

 

[Rebel Souljah]

pictures?

^^^i agree, pic will help

 

[sabotage]

stress marks because of the new guys sounds like.>pics would be nice

 

[silverdragon]

colour change was probably due to stress from the new addtions to the tank but like previously stated above, a pic would help.