This (from the seriously fish species profile) rings a bell, though I'm by no means a disease expert and haven't personally seen "hole in the head":
This species should never be added to new or otherwise biologically immature aquaria. When conditions deteriorate it becomes susceptible to a condition similar to that referred to as head and lateral line erosion or hole-in the-head in other species which initially manifests itself as small pits formed by eroding flesh around the head and lateral line pores.
Could the water quality be deteriorating, or substrate need cleaning? The same article warns against large water changes, but I'd look at water quality. I'm sure others more knowledgeable will chime in.
My best guess is that it is fungus from a scratch and shouldn't be treated; however that is not the reason the fish is in the corner. Rams are fairly delicate and require much more stringent proper care than many common fishes. Do you know the temp of your aquarium as well as the parameters (ph, nitrate, nitrite, ammonia, ...).
So an update, showed the lfs a video of the ram who said it looks like fungus, brought some water treatment for the tank & put that in but sadly he died that night. I have come home today & found my other ram has died, along with my pearl gourami! Any ideas what could be going on? Water parameters all seem normal & other fish all seem fine?? I only done a 50% water change 2 days ago so not sure what’s happening.
Combination of of temperature, nitrates and general pollution (if 25ppm was a normal and regular level I mean). In my limited experience Rams are sensitive to everything. The gH seems fine, though I expect Rams like it even lower where possible. pH seems a little high; maybe the water company are adding kH to buffer the water? I do not know if soft water fish are harmed by high kH or just gH. My Ram seemed to die from a tummy bug after engorging on a dead shrimp, but I was foolishly trying to do a medium heat water to suit both the Ram and the Cories, otherwise he may have fought off the illness.
I read somewhere ages ago (magazine or even this forum I expect) that our hobby isn't fishkeeping it's water keeping. Fish that people have found to tolerate a wider variety of conditions probably do so because that's what they have evolved for. Years ago Rams used to be labelled in all the handbooks as "expert" because they seem to be one of the species that do not seem to tolerate any of the minor mistakes we all make occasionally, especially when new.
The death of the gourami at the same time is more concerning. What do you mean by "fine" parameters? And how often do you check them? If you are overstocked, maybe the tiny amounts of ammonia that appear before they "dealt with" are proving to be slightly too toxic for the fish due to the slightly alkaline pH.
Test your water, monitor the health of the fish. It's possible your tank is mature and the water is indeed fine, at least for the remaining fish; the pearl gourami death might just be an unlucky co-incidence. But it would be best to check now when you have the chance to at least do some extra water changes if you think you need to before there are more deaths.
As noted 75 is way too cold for german blue rams and that alone would have killed them. Once upset they are difficult to recover; they are not a fish that one should start with. There is a similar named but less colorful fish called bolivian ram that are far more hearty and can not only can handle cooler temperature prefer cooler temperature. Alas they should be kept as solo fishes and not in group. The gourami we would need more information like how long you had it and exact parameter of your water. It could have been bacteria infection but it could be that something else. Saying 'water parameters are fine' provide no details and hardly deserve a response.
Your tank is likely cycled since nitrate is 25 and nitrite is 0 but did you 'clean' the filter by replacing the media? that is a common mistake which can break the cycle of the aquarium.
In any event we would need a whole lot more details if we are to provide even a suggestion as to what happened.
The parameters are the same as I said previously- temp 25-26 degrees, ph is 7.5, nitrate 25, nitrite 0, gh 50-60. When I say fine I mean they haven’t changed from what they always are!
The gourami I have had for about 6 weeks. The last couple of days I noticed he wasn’t swimming about as much and mainly staying at the top of the tank & by the filter, as was the other ram. I also noticed he had a long string like coming out of him the other day, which I assumed was poo but wondering now if it was something else?
the only filter media to have been replaced is the weekly bio pads - the other media I just swirl in the empty tank water to clean, doing half of the filter each week - alternating it. Water change is done 50% weekly.
What are the bio pads? Filter usually has filter floss and sometime ceramic rings; if the bio pads are filter floss it should not be replaced that often if at all.
If the temp was still 25 it is quite understandable that both rams died and a bit surprising it lasted that long. It sounds like the gourami became ill a few days after you purchased the rams and it is quite possible they had some sort of disease that spread to the gourami. As to what specific disease it is hard to guess.
Rams are notoriously delicate - I've seem some argue (thought I am not convinced) that they are harder to keep than Discus.
The original picture, to me, seems to be Hole-in-the-Head and Rams typically (but not always) develop this disease when exposed to environments with poor water quality (but it can also be caused in part by poor nutrition). Once the fish begins to develop HITH it can escalate pretty quickly as a site for secondary bacterial/fungal infections. If you joined one of the Facebook Ram Groups you'd be surprised at the number of members that post pictures asking what's wrong with their Ram to discover it's HITH disease --> I'd say 6/10 posts asking people what's wrong with their ram is HITH disease.
I would suggest, though it will always be impossible to know, that a combination of improper temperature and high nitrates (25 is high, should be less than 10) caused this to happen. The additional deaths point very clearly to a water problem. Healthy fish don't just die (thought TBH sometimes rams can be the exception due to their delicate nature).
What are the ammonia and nitrite readings of your tank? Can you provide an updated Nitrate reading? That number will rarely stay constant as the nitrates increase with every feeding/fish excrement. I would recommend doing a large 50% water change w/ substrate vacuuming if possible.