which of these fish should i get?

ok, ive got a 38gal tank, 36"L x 12"W x 20"H.
my fish are:
3 colombian tetras
1 oto cat
1 angel
1 ruby shark
1 whiptail pleco
1 bristlenose pleco
1 clown pleco
1 blue acara

my filter is an ac110, and i do 30% water changes weekly.

plants are:
lots of cryptocoryne wendtii
some anubias nana
hornwort
a small java fern


i want to get two kinds of fish when i go to my lfs. heres what ive been looking at:

african brown knife or striped raphael catfish or Hypostomus punctatus.
AND
single blue gourami or blue gourami pair or 6 red eye tetras


i know the knife and catfish are predatory... would I be able to move the oto to a 5gal? the 5gal's already running with a dwarf gourami and mystery snail in it.

and, no matter what, i will fill out my tetra school.
so, which two types of fish should i get?

P.S. ive got this thread up on AC as well. i just want lots of opinions.

smpage;3707108; said:

What a wierd size tank! Seems just a tad overstocked if you add more but with the right readjustments I'd go with the knife AND the raph cat.

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thats what i originally wanted.

what adjustments would i have to make? could i just remove the oto and tetras?

Jakob;3707160; said:

Get another whiptail.

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havent seen them around here... got him when i was a long ways away from my house. if i find them, ill get one.