From your pictures it would seem that you have a Batrachomoeus trispinosus (a toadfish that is sold as the FW lionfish), it is one of the larger ones and sometimes reaches one foot in length. It has venomous spines that can cause a wound that hurts for days. It can eat fish more than 1/2 it's own length and likes hiding and perching spots, not real active and somewhat nocturnal, it is adabtable but prefers brackish water 1 tablespoon salt per gallon is recomended for best health and growth), it has a tendency to get fin rot and fungal problems if kept in full freshwater. Even 1 tbs salt/5 g will help.
The morgunda sand goby is probably a Oxyeleotris marmorata (also called a marble goby). it is also very adaptable and can live in full FW with no problems. They don't move much but sometimes bury themselves, when they feed or you try to catch one they are very fast. They like a little salt (1 tbs/5 g is fine), They can reach 26". They eat anything and everything. including trying the occassional finger, I once had on that ate an 8" LMB when it was only 10".
The TSN gets large, 40" is not that unusual, and can go from 2" to 15" in less then 10 months