Otos and Amano shrimp acting strange

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Registered Member
Nov 11, 2019
So I’m about 3-4 months into my first fully planted tank. The tank is about 12 gallons, with the original inhabitants being 4 Indian Dwarf puffers and a large colony of MTS living in the substrate. The tank is heavily planted with an assortment of Val, rotala, Christmas moss, duck weed etc. It’s being filtered by two well cycled and decently powered filters. No CO2, powerful planted tank light, adjustable heater. The hardscape consists of a lot of intricate spider wood, which makes for a ton of hiding places with the thick mat of moss that covers it.

Water Parameters:
Temp:78-80 F
pH: 7.4-7.8 (there’s pretty basic tap water where I live)
Ammonia: 0
Nitrites: 0
Nitrates: 0-5

About 2 months ago, I purchased a group of 3 otos from my LFS to add to the tank. They did perfectly well in quarantine for the month they were in there, so I added them to the display tank. For the first couple days, all they did was swim up in down the glass in one corner of the front of the tank, but after about 4ish days, all but one were spending most of their time in the back of the tank away from the puffers chilling on the val and wood. One of the otos, however, is still acting extremely stressed, glass surfing constantly in the same corner. Occasionally the others will join the one oto and glass surf for awhile before returning to their usualI noticed that for those first few days, the puffers showed little interest in the otos, but then I noticed that the otos fins showed clear signs of getting picked at. With a revamped feeding schedule for the puffers, that little bit of aggression seemed to go away and their fins seem to be recovering.

As of yesterday I added 3 amano shrimp to help with a syringe algae problem that had started to develop. The puffers showed initial interest in them, but they quickly started ignoring them. However, the shrimp have been swimming around the tank frantically, glass surfing with the oto, and climbing into the hang on the back filter. I figured maybe the Flourish I use once a week after my weekly water change might be affecting them so I did a large water change, but the shrimp are still acting strange.

I imagine this could partially be because the shrimp were just added but their frantic swimming seems to be stressing the other fish out. What am I doing wrong? Is the tank over stocked? Is the pH too high? I would really like to get to the bottom of this before I lose any fish or shrimp. I care deeply about all of them and have invested a lot of time and money into trying to keep them all happy. Any advice is welcome!