READ OUT LOUD. Choose which marked text you prefer to practice with - macrons in verse form, or macrons in prose order, or accent marks in prose order, or focusing on the meter. You will find materials for all of these options below. :-)
VERSE MACRONS. Here is the verse text with macrons:
Delphīnī īnsīdēns vada caerula sulcat Arīon,

Quam sit avārī hominis, nōn tam mēns dīra ferārum est:

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Arīon, delphīnī īnsīdēns, vada caerula sulcat, et hōc sonō aurēs mulcet et ōra frēnat. Quam dīra mēns sit avārī hominis, nōn tam ferārum est: et quī virīs rapimur, piscibus ēripimur.
STRESS (ACCENT) MARKS. Here is the prose text with accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Aríon, delphíni insídens, vada caérula sulcat, et hoc sono aures mulcet et ora frenat. Quam dira mens sit avári hóminis, non tam ferárum est: et qui viris rápimur, píscibus erípimur.
ELEGIAC COUPLET METER. Below I have used an interpunct dot · to indicate the metrical elements in each line, and a double line || to indicate the hemistichs of the pentameter line.
Delphīnī īnsīdēns vada caerula sulcat Arīon,

Quam sit avārī hominis, nōn tam mēns dīra ferārum est:

IMAGE. Here is an illustration for the story (image source).

What follows is an unmarked version of the prose rendering to faciliate word searches: Arion, delphini insidens, vada caerula sulcat, et hoc sono aures mulcet et ora frenat. Quam dira mens sit avari hominis, non tam ferarum est: et qui viris rapimur, piscibus eripimur.