I am bit confused. If you place the fish in a fish tank, you will be mostly / only observing them sidewise. If it is a pond they are going into, then you will only see the top view. In the latter case, it sounds like you have already found your unicorn, an Ictalurid species.
In the former case, what you describe reminds me of Pseudopimelodid and Auchenipterid catfish families (check them out in Planet Catfish Cat-eLog), but they are primarily or only diurnal hiders. If you lean a large rock against the front glass, and this'd be the only protected spot, they will make their hideout there and you will see them 24/7, but they wouldn't be active, you will be looking at an interesting log that changes stance once in a while, until the feeding time, then all the wigglesness will come out.
There are great many other smaller catfish that are attractive too, just not necessarily with large round pectoral and caudal fins and funny wabbly swimming. May I interest you in, for instance, a Black lancer or Harlequin lancer catfish, or a school of glass catfish, or a school of pictus catfish, or a Chaca chaca, hoplo catfish, corydoras, smaller Doradids like from Hassar or Doras genus, Bagrid from a Mystus genus, e.g. upside down Asian catfish, or a Synodontis, or a dwarf giraffe catfish?
An example of rock against the glass:
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