You can use filtration without carbon, which might help in keeping the tank really clean. Quite often you can find filters (exterior ones are great) at garage sales for not much, even a box filter might help. Other than that, there are inexpensive ones at Walmart, etc. Will he be fine? Yes. Keeping the tank clean is helpful, but given the size of your fish and the size of the tank, not a biggie. I tend to put filtration in because I usually leave them in the tank either until the fin heals, or until I get around to taking them out...which is longer than 72 hours. I put in a shubunkin back in March and am just now going to put him back in the pond. Good thing I did, or he would be dead by now killed by car washing solution. :/ You can also siphon up the poo while doing your partial water changes so the filtration really is not a big deal. I've had great luck at healing the wounds like this, so I think you did wonderfully well by not returning the fish.

From the pictures your goldfish look like they might be fantail goldfish? The one that died looked like it was pineconing which is dropsey almost always fatal. Fantail fish seem to be more prone to this and to contipation especially if you feed them floating pellets. If you feed your fish cooked and skinned peas two times a week it helps with constipation and swim bladder disease which fat bellied fish like fantails are prone to.I have used melafix in a tank only to treat finrot problems but only when it gets about half as bad as your fish. Salt also works but I've only used salt in a tank as my pond has plants. By the way your water in your first picture is incredibly clear. How'd you do that? Sorry for the loss of your fish. Ammonia spikes can cause fin damage--your white fish is a good indicator of water parameter changes. They will get pink streaks if the water parameters especially ammonia are off.

If the fish was fuzzy all over, it was almost for sure a fungus called Saprolegnia, or SAP for short. It is nasty. It usually attacks skin that is already damaged in some way....parasite bite, sore, scrapes, bacterial skin or fin issues, etc. SAP lives in all ponds. It is the fuzzy stuff you see on uneaten food. Keeping the pond clean goes a long way in reducing the levels of fungus in the pond. When SAP does get on a fish, it sinks roots into the fish's skin and releases toxins, making the fish feel bad and eventually killing it. Treating it by pouring something in the pond is practically useless and will probably damage the bio-filter, which will cause ammonia problems. The most effective way to deal with SAP is to sedate the fish (8 drops of clove oil in one gallon of water, wait until fish is calm and begins to roll over, then he can be handled). Place the sedated fish on plastic wrap and cover his eyes with plastic wrap to keep them from drying out. Carefully scrub the SAP from the skin with a Q-tip in peroxide. Be careful not to get peroxide in the eyes or gills!! Then dab a little malachite green directly on the treated area and seal it with denture powder. Place the sleeping fish back in the pond over aeration (I usually hold them in the net for this step, until they are away....takes about 5 minutes). Watch the fish very closely for a recurrence as SAP often comes back. But before you do this, please make sure you get me a picture first....it may NOT be SAP, and I'd hate for you to take such a drastic step in treatment if the fish does not need it.

Can you tell me what else is in there ie live plants, silk plants so on, and WHAT type of gouramis... gouramis when they mature get territorial (I am glad you have females not males in there, lol)... and often females get more aggressive as they age... as you already know bettas do jump, it's a natural thing when they catch insects in the wild. But she is not suicidal nor is the other fish assisting her... it could be aggression by the one betta towards the other, and she is avoiding her by jumping (escape behavior) and luckily gets stuck to the side as opposed to landing on the floor. Also, fish jump when the water chemistry changes (for the worse) so rule this out by checking everything. Cories btw should be kept in schools... at least 3 for this size tank. (larger school better, but cories need more space to swim about so 3 at least as to not overstock). I'd find another tank for the gouramies. So, she is not jumping intentionally as we know of it, but either jumping for food (but would do this when you come close to feed) (I had one that jumped about 8 inches as she saw me coming towards enclosure to feed her - lucky she was in a huge 50 gallon globe kept 2/3's full, so she would flop back into the water). 1 - check water parameters... 2 - the fish pushing her up probably is being aggressive... females can fight to the death as easily as males (I had a group all sisters, in huge 30 gallon fully planted, and when they matured pecked each other (and if done long enough they get stressed, sick and die) so had to put each into their own tank. I think you might have missed the aggressive behavior, and the "pushing" is actually her chasing biting aggression towards her. She is jumping to avoid if this is so. When my four at first got along, I'd then (as they matured) notice some in hiding, with number one top dog, running after the second strongest (like ducks they will pick on down the line)... they would fight just like males and I was stunned at the eventual ferocity! I could see her just nip at the others face... and I took her out fast - that was that. Gotten along for a while then all changed. Also, if gouramis are in need of space their aggression or even tension can spread to others - all in one tank are affected by the other fish - it spreads. As someone said one on another forum, put a lot of people in an elevator and see how you feel after a while. What looks like lots of space to us, due to each species needs may not be.. both bettas (females included) and gouramis are territory, and in nature are not in such close proximity, but loners unlike schooling fish. (save for breeding, and even then female bettas have even killed males). 3 - gourami (even dwarf) are in too small of a tank, and need a planted tank with enough space for each to claim their own territory. Again, learned this the hard way - 40 gallon with four dwarf blues. At first about one year fine, then each claimed part of the tank, then top dog wore down one (died before I got a clue and did more research on natural biotypes) and had to separate them and it was with tons of plants and wood. Just part of their nature. Can you put some java moss, other floating plants around edges at least.. eventually her scales/slime coat can get damaged (make sure lid is on tight to keep moisture on sides) if she is truly sticking and Flexibacter columnaris bacteria (looks like fungus but deadly) can set in. Even with plants if she is still jumping, eventually it will catch up with her.. they can breathe out of water for a while but if she dries up not good at all. (salt water bath can save her, but need to graduate it up and then back down dose wise slowly over time)... When fish (not bettas or those that catch insects and jump doing so) jump it is most often always an escape response - so try to observe/find out what she is escaping from. You are correct in assuming that this is not healthy for her. (guy on another forum had a small tank with aggressive barbs, fish dying right and left (cowering neons picked off one by one - gee could it be the barbs says he) and even the shrimp tried to escape (natural food for most fish esp those with teeth!) and he would find them crawling out of the tank to escape! No one wanted to be in the small tank (needed at least a 30 and he had them in a ten!) with those nippy barbs! (Not to mention all needed diff water chemistry). He is insisting on keeping what he wants so fish will suffer. Since she is doing this recently and not just during feeding time, something is wrong in her environment. Water chemistry, aggression (and it can come on suddenly after ages). (maybe transfer her water add some plants for security and put her in another tank (with lid) to see if she still does this behavior ) (to reduce stress, cover tank partiall and low to no lights for a while until she settles down)... Also, best to transfer bettas in plastic (like chinese soup tub) container as their tails/fins are one cell layer thin and nets can injure them. Also much less stressful for them (clear easy to do, just float under water and gently scoop them up - I add a bit of moss while taking it out and be careful they jump when stressed - lid on fast! lol) (as you can see many decades of raising bettas/fish with all sorts of experiences, lol). I once put a huge female guppy in another large planted globe with one of those seperated females. When I can back a few minutes later I was aghast to see this great guppy leaping out of the water like a skipped rock (like when as a kid you skim a rock over water, just like that bamm bamm bamm)... the female betta was chasing her down like a madman and she was running and jumping (escape) for her life... fish can be killed very fast by their powerful jaws. I of course ran for a net and took momma guppy out pronto! Try to remember if anything changed before this occurred. Best, let me know how it goes (my email stopped coming ages ago, so sherryazure@yahoo.com or sherryazure@gmail.com). Sherry