bigfatfish - Moving the hardscape a little in each water change would be a PITA because I have very heavy stones, and I have cryptocorines, sagittarias and eleocharis that don't like to be moved. That's why I really did plan the decor.
speaktree - I was thinking of floating plants such as duckweeds or water lettuce (pistia sp.). I planted my hornworts among the rocks since they begin to rot if I plant them in the substrate.
Well, I think I have good news.
Today I made a water change and I raised the salinity from 2 g/L to 5 g/L (SG 1.002 at 25°C/77°F). My water parameters are:
Ammonia: zero
Nitrite: zero
Nitrate: <5ppm
pH: 7,5
KH: 8°dH/143 ppm
CO2: 8 mg/L
GH: 30°dH/535ppm
Temp: 29°C/84.2°F
SG: 1.002
Salinity: 5g/L
In the beginning they used to pace up and down the glass after feeding time. Now that I raised the salinity they were fed and then they went to take a rest instead of pacing as they used to do. After that I noticed they exploring the java moss... That was the happiest moment that I experienced!
I think there are factors that together prevents them from pacing, such as:
-Medium-low light;
-Some tall objects such as plants/rocks/woods among décor to breake up the lines of sight;
-Not overfeeding to stimulate them to explore and hunt for food;
-And the most important, proper water parameters (including the presence of salt in the water).
I realized that there’s not one unique thing that will stop them pacing the glass however a number of factors that make them feel more comfortable in the tank.
I hope they keep up that good behavior.
I really like to thank each one of you for your time and your advice.