Bichir with a lump on its tail/swiming erratically

[kumarthecrippled]

Hey everyone- I am brand new to this forum as a member goes but have been viewing it as a guest for the past year or so. A year ago I got back into the aquarium hobby and wound up getting an albino sengal bichir after instantly falling in love with him at my LFS. He (i think its a he) is currently housed with 4 other giant danios in a 30 gallon setup and is approximately about four-five inches long. They were all initially in a fifteen until a few months ago when they all finally got too big and I nabbed the 30 off a friend- I know its still a little on the cramped side and intend on getting a larger tank (probablly in the 75-100 range) in the near future. I've never had any issues with the guy until now though- he suddenly seems to have gained an odd, slightly inflamed lump right at the tail and I have no idea as to why (see picture below).
Water parameters are fairly decent- I've had a recent gradual spike in PH that I've been correcting with ph regulator (it slowly jumps up to somewhere around 7.8 when I normally try to keep the water between 6.8-7.2). Amonia always reads at 0 (or rather the liquid test kit shows yellow so right where it should be/below 1ppm) and nitrites and nitrates are also in the healthy range for these guys
My bichir got the lump not long after killing my golden gourami that I was housing in there while waiting for the old 15 gallon to cycle- though the gourami itself was seemingly healthy- just on the smaller side and my bichir didn't eat him so much as take a bite out of the guy Two days later he got the lump.
The other thing I'm worried about is ever since I transferred him to the new tank and especially since this lump (which has been there about a week now) he has been swimming very erratically around the tank- its hard to describe outside of he just sort of freaks out more than normal.
Idk if he's just constipated or has a large piece of food stuck there- what really worries me is that there is a bit of reddining along the fins along his back near the swollen area. would a salt bath help? I'm willing to do so but I don't wanna put any extra stress on the guy than needed (he is the absolute worse to net/cup to move around as I discovered during the upgrade of tanks).
The only other notable change is that my danios mated recently and I have a breeder tank of the fry at the top of the tank until they are big enough for me to transfer to my fifteen so they can grow
Any help/advice would be much appreciated as I would love to keep this guy alive and kicking.

 

[Dr.B]

I may be interpreting the picture wrong but it seems as though his anal fin is the area of concern. If that’s the case then it appears that his anal fin is just becoming bulkier as males do once they age. As for the freak outs, that’s typical when you move a fish to another tank. It’s a different house and he doesn’t know everything around him so he’ll get spooked easier. That should stop in a few days/weeks once he gets more comfortable. As for the anal fin, I don’t really see anything to be worried about. It looks as if the lump is just above where his anal fin ends? If it stays around the size it is now then it’s just him maturing. If it begins to get larger then that’s something to worry about

 

[BichirKing]

exactly^
also the substrate could pose a threat if they swallow one of those pebbles. sand is best for these guys.

 

[clm08k]

Looks just like my albino. He sometimes had a bulge there too, but he seems normal. However, the erratic behavior might mean something. Can you post a video?