I'm Just Not Sure What To Do... Question

So in my town, I,m pretty much the go to girl when someone has a fish that they dont want. I have been given around 60 goldfish won at the city fair, and lots old pets that either got to big, became to expensive to care for or the owner just got bord of them. In my town, fish are seen of more an accessory or a easy matnence pet for your 5 year old. Countless times, people come to me asking why there fish is half dea, because they dont know that you have to use water conditiner, or that a filter is nessesary for your fish. I shouldn't be complaning though, because I love my fish and its turned into a passion of mine. I have a 5000 gallon pond in my back yard for all the goldfish and koi people have given to meover the last few years. I also have a 175 gallon tank for my 7 angel fish, a 125 gallon tank for my red discuses, and a 50 gallon tank I filled with some glow fish that my nephew loves. But none of my fish or tanks can hold a candle to my 175 gallon tank that has my betta and up untill recentaly, had 3 pictus catfish. I know that these two types of fish are not good in a tank together but i had receved them as a gift and they were my first introduction to owning fish. About a month after they were given to me, I was doing reserch and found out all tfhe possible problems that go along with housing them together, so I decided that I would by a new tank for my betta, and leve the pictus cats in the 175 gallon. but when I did that, the cats and the betta were unhappy, and they stopped eating. They hadn't had a problem with the betta before so I put them back in the same tank and they started eating again. For years they would play together, and I didnt have any problems with them. For the first 2 years I had them I tryed to separate them a few times. But whenever they were separated they would stop eating and stop swimming around the tank. after this happening a few times, I decided to just let them be. They were happy and getting along, I never once had a problem with aggression or the fish nipping at one another. I figured if its not broken, why try to fix it. Because I eded up with the Pictus cats by enhareting them from my grandfather when he passed away, they were already 6 years old when I got themn 4 1/2 years ago. Fast forward to 6ish months ago, I went to work and when I came back, all the pictus cats are dead. I'm still not sure what happened. There was no external sighn of trama or illness, and sushi was absolutly fine. I checked the ph, the water temp, I checked for any sighs of ick or fin rot. I came up with absolutly nothing. I did a water change and cleaned everything just to be safe. Now sushi was in the tank by himself and looked horable. I have tryed everything I can think of. Ive tryed putting him in a smaller tank so it wouldn't seem so empty, I tryed putting him with my friends pictus cats and he became really agressive. I tryed putting him with other types of fish that he might get along with such as a panda cory, a loach, neon tetras, and Clown Plecos. He ends up being really agressive to anything even if I put him in the other fishes tank so he isnt teritorial. I have tryed adjusting the water temp, changing his food, feeding him his favorites, and i tryed putting him with my boyfriends female betta during mating season. Nothing works!!!!! He is very pale, barely eats, and will often just ram himself into the side of the tank. I know he can see because he will follow my finger like he alwase would. Anyone have any ideas. I dont know what to try next. Sorry for the insanly long post, any sugestions help.

 

According to your profile, it seems like you don't know what the nitrogen cycle is. Is there any way that you can get a liquid test kit to test your ammonia, nitrite, and nitrate levels? That would help a lot in determining what is wrong with your Betta. I'm sorry I couldn't help any more than this.

 

As seemingly silly as it sounds fish more than likely have feelings too. Sushi just lost friends. Its traumatizing. Make sure you interact and monitor Sushi. Perhaps after a few days color and appetite will return. Seeing as how you have had the tank established for so long I highly doubt it is a water chemistry issue. The pictus cats were at least 6 years old? Sushi more than likely has some aquatic version of separation anxiety.

 

It's highly likely that they died of old age. I believe Pictus Catfish live 8-10 years. So if they were 6 years old when you got them, then they would have been 10 years old when they died.

Sushi's probably trying to get over the death of his friends (as NavyChief said). But if you want to give him other friends, I'd use whoever he was least aggressive with and start slowly (and when I say slowly I mean over the period of at least a couple days, if not more) introducing him to that tank. The process I've had the most success with is: 1) move the tanks right next to each other for a day or two, 2) either divide the tank or put the betta in a breeder box for a couple days and 3) if the betta is still acting aggressive after the past several days, then it's best he's left alone. Otherwise, put him fully in the tank/remove the divider and watch him closely for the next several hours.