Not necessarily. If you're thinking that a broad spectrum antibiotic (IV or otherwise) would be administered in this case for empiric coverage based solely on wound size, you would be incorrect. On the other hand, accompanying symptoms including any signs of infection including febrile would likely get the order. Associated medical comorbidities and renal/hepatic/age considerations would factor in strongly for the decision to treat empirically or not.
Let me describe what I'm seeing in those 2 latest photos: there is significant peeling and blistering of adipose tissue and fascia associated with the wound and its margins. The pink you're seeing underlying these wounds is muscle (an indication of just how deep these wounds are). I still do not see any frank signs of fungus or other signs of localized infection; very good signs.
It is a good sign that he is eating. Try to identify any other changes in behavior (including bowel habits) and relay them in this thread. It will take a very long time for this wound to heal.
During his recovery, you can start to think about what to do with him long-term. This species requires a much larger tank than the one you have been providing him. Frankly, it is totally inappropriate for any home aquaria. Here's an example of how big these get, living to 20 years in some cases:
As always, this is my opinion for best course of action. I will say that I am disappointed to read some of the suggestions made in this thread from several users. The decision is, of course, ultimately yours. Some considerations:
1) If you feel compelled to treat with an antibiotic, there are a few things you need to understand. You have no idea what infection, if any, is present. Therfore, you should select for broad spectrum coverage. Maracyn and Maracyn 2 should be used together in this context. These meds do kill off biofilter bacteria so you must watch water chemistry very carefully. Fortunately, there is less risk because you will continue with daily water changes. If you use carbon, remove it from the filter. After you perform your daily water change, dose the tank; NOT before. If possible, try to find an antibiotic from Seachem called Kanaplex or Neoplex and use ONE of these instead of the Maracyn combo. These meds are highly effective and do not affect the biofilter. Any medicine may irritate the wound directly and stress organs in an already weak fish. In case you're wondering, IV injection for fish is possible, but inappropriate to consider at this juncture.
2) A melafix and/or pimafix combo will cause direct wound irritation and likely accomplish little.
3) Topical ointment application for wounds of this size will cause direct wound irritation, delay healing, and cause further pain/stress.
4) Provide a varied diet and maintain your water changes. I'll say it again (as echoed well by Karl earlier); the only thing seperating this animal from death is nascent immune and healing power. No medication will help unless he is optimally positioned to fight towards recovery. The best things you can provide to assist is extra clean water (temp. matched and conditioned), subdued lighting, low stress, and high nutrition.
Finally, Melody gets brownie points for making a post using the words granulation tissue :headbang2:
