Question
I have two 6'' pots of Venus flytraps in an aquarium with water in the bottom.  The plants in one pot are doing just fine, but the plants in the other pot are not doing well.  The plants in the bad pot have struggled to grow properly.  Leaves seem to have a shortened life; they blacken, beginning at the edges, and then die before their time.  I have lost several plants in the bad pot.  The traps that form are for the most part non-functional; the edges of the traps, particularly the distal edges, curl inward and result in a malformed trap that is pear-shaped in outline.  I have been growing at least a few carnivorous plants about all my life, and I have seen this phenomenon before on flytraps but not to the extent of my present problem.  The trouble began last year.  I had a few plants with mis-shapened leaves that I transplanted into fresh soil with other plants that were normal.  I figured the abnormal plants would recover and the normal plants would not be affected.  I was wrong.  The cool-down in the winter and the resurgence of new growth in the spring did not return the plants to normal.  I have never seen this happen before this.

Answer

My Beloved Thriving Ve  

My Venus Flytraps   Hello Keith
         I'm going to have to asking so questions first about this troubled  pot.  The new soil is made up of what? What kind of pot are these plants planted in and what are they made of? Have you Venus Flytraps had their dormancy and if so for how long? What kind of water are you using and the lighting what kind how much lighting in a day?  I'd like to see the different plants that are in this sick pot, can you send a photo of it?
         A lot of things can make a carnivorous plant sick and burn out it all most sounds like dormancy issues or the soil being to rich making the plants not form their traps and have burned leaves. As a little note sometimes just because one pot is doing well and the other is sick does mean that it can't be a all over problem for your terrarium. We will have to go over a full check list and then we will have the problem taken care of.  I want to thank you for trusting me in helping you and together we will fix this problem with your beloved carnivorous plants. Looking forward in helping you and soon my friend!  Later then, Dan (Daniel Lee Bowen)