Tiamat:
Maint Life is _very_ long. Reduce it by 2/3.
Gauss cannons as main weapons seem to be a strange choice. Their very, and I mean _very_, short range will probably bite you in the behind, but if you insist on using them, I´d put them in turrets with x4 tracking firecons, so they are good for PD as their main mission and for offensive use as a secondary mission.
Gauss cannons don´t need no power plant, so you can scrap that.
I see you have a CIWS. The thing to know about them is, that they only protect the ship they are mounted on. Personally, I prefere another turret mounted gauss, that will protect the entire task group, but to each his own.
Victory:
Half the maint life.
A salvo of two slow missiles will get you nowhere. Even the most basic PD setup will be able to deal with that.
You´d want your sensors to see further than the range of your missiles, preferably a _lot_ further. If you use a dedicated sensor ship or put those actives on each combatant is up to you.
If you do the former, I´d suggest keeping the ones you have as a backup, in case the sensor boat buys it.
With no PD weapons (except for the CIWS, which has its own sensors), you don´t need the res-1 active.
Your missiles seem very weak for a size 5. I´d suggest investing heavily in missile tech and designing a new one.
As it is, they have a rather short range, their warhead is pretty weak and the chance to hit a moving target is abysimal (yes, they realy are not good

)
Edit: Ok forget what I said about a sensor ship, as I just saw that your Hump fills that role.
Hump:
You can loose the res-120 active, as it can´t see anything, your res-150 can´t. You might use the saved mass to up the res-1 active a bit. Yes, it has a 1 million km range and you only have gauss cannons to shoot at enemy missiles, but that range is against a 50 ton target (i.e. size-20 missile). Against size 6 or smaller missiles, that range is a lot less.
Fleet Commander:
Personally, I only put basic actives on my jumpships. They will stay at the jump point while the fleet goes in-system to look for trouble and I do _not_ want to draw attention to my ride home by activating a huge homing beacon.
Large passives are the way to go in my book.
Aside from that, more armor is always good on your only means of getting home again.