Worried About Gourami

[Samj11]

Hi, all! I don't know if this necessarily constitutes as an emergency so I apologise if it doesn't, but I'm worried about both my 100L and 300L tanks. I lost a pleco from the 300L a week ago. He was very off colour and thin. I've also lost a few of my tetras from my 100L tank even though they showed no signs of anything being wrong with them. I've been carrying out big water changes weekly and thoroughly vacuuming the gravel so I don't think it's bad water quality. It's probably best to note that my loaches have been flashing too even though there's nothing about their appearance that particularly concerns me (don't look skinny or have white spot) but they've got to be flashing for a reason. I added a wormer to both my tanks a few days ago as they were due one just to make sure it's not anything internal.  
 
Below are some pictures. They're the best quality I could get and he wasn't keeping still much which was a pain.
 

 

 

 

 

 

 
Sorry if they're not clear. I'm worried about the mouth and the top and bottom fins. Can you guys see why I'm concerned? Or am I just seeing things? He does seem skittish and he's at the bottom of the tank more than usual, which is unlike him. 
 
If I had to guess, I'd say it was a rot or fungus of some kind, but I can't be sure. Is it mouth fungus I'm dealing with? If so, can anybody recommend some good medicine? Bear in mind it'll have to be suitable to use with loaches in the tank, who I know are sensitive.
 
My fish are important to me and I love my gourami/loaches especially so I'd really appreciate some immediate advice. I'll be ordering some medicine ASAP.
 
Thanks, guys!

 

[Meeresstille]

Do a search on Columnaris if that looks like what this could be. 

 

[Samj11]

That disease I read is fatal very quickly, which doesn't seem to be the case here. I'm not sure if it's that.

 

[Samj11]

Update: I've repeated the medicine daily as per the instructions while symptoms continue but I think there has been improvements. There's significantly less flashing from both of the fish that were doing it, my gourami is spending a lot of time back at the top of the tank where he belongs as he was spending most of the time at the bottom (which was the first sign that something was wrong) and he's swimming around more and getting a bit of his moody personality back (chasing the leopard danios away if they swim into his area of the tank). 
 
The fins look like they've improved a little too (I think). How long does it take for them to heal/grow back? 

 

[Meeresstille]

Sounds promising if they seem to be getting better. Are you treating them for fin rot? The time for the fins to grow back will depend on how badly they were damaged. If it's just the ends of the fins it shouldn't take too long. If they have been damaged all the way to the body then sometimes the damage can be too deep and it can't be repaired any more.
 
There are different strains of columnaris. Some will progress very quickly some take longer. Do you see any redness on any affected areas? What made me think it could be columnaris is the picture with the cottony looking stuff on your gourami's mouth. 
With this disease it can sometimes just affect the gills which could explain the other fish deaths you saw, with no apparent signs of a disease.
 
Let's hope your gourami will continue to improve. Good luck!