Limits to teachable skill, rearing fish (5)
I believe the answer is:
tetra
'fish' is the definition.
(tetra is a kind of fish)
'limits to teachable skill rearing' is the wordplay.
'limits to' means to remove the middle letters (only the edge letters are used).
'skill' becomes 'art' (both can mean a talent).
'rearing' shows that the letters should be reversed in order (as in a horse rearing up).
'teachable' with its middle removed is 'te'.
'art' in reverse letter order is 'tra'.
'te'+'tra'='TETRA'
(Other definitions for tetra that I've seen before include "Denoting four (prefix)" , "rarely seen flower" , "With four parts" , "Bright tropical fish" , "Brightly coloured aquarium fish" .)