_Bella_:
Which part of Tenerife are you on? I visited and dove there many many years ago and it wasn't nearly as exciting or diverse as your pics.
Dear Bella
What is diverse? As of 1991, there were 553 species of fish in the waters around the Canaries, and more have beeen discovered since then. On a single dive, entering from shore and diving to a depth of around 20 meters, you are likely to see:
1.angel sharks
2. parrotfish
3. several species of stingray
4. syngnathidae (pipefish and seahorses)
5. trumpetfish
6. baracudas
7. weevers
8. gurnards
9. lizardfish
10. scorpionfish
11. black-tailed combers
12. painted combers
13. groupers
14. several species of morays
15. damselfish
16. gobies
17. blennies
18. hogfish
19. various species of wrasse
20. frogfish
21. stargazers
22. several species of bream
23. several species of tuna
..and that on a typical day of typical viz (30m). In August-September-October mantas can be spotted off the southern tip of the island. Various shark species (makos, blue sharks et. al.) are around all the time, but you will usually only see them on blue water dives.
I find that fairly diverse! Atlantic diving requires more attention than coral reef diving, but is just as rewarding.