This seems to be a different conjugation pattern? If it was after the pattern of έγω, it should be κολυμπει, should it not? Or after the pattern of είμαι, κολυμπαι?
Depending on how you count it, there are three major patterns for verbs: those in unstressed -ω, those in stressed -άω/-ώ, and those in stressed -ώ.
κολυμπάω/κολυμπώ belongs to the second of those groups.
stress on stem:
- λύνουν (λύνουνε)
stress on ending, -a-:
- αγαπάω, αγαπώ
- αγαπάει, αγαπά
- αγαπάμε, αγαπούμε
- αγαπάνε (αγαπάν), αγαπούν (αγαπούνε)
stress on ending, -e-:
- θεωρούν (θεωρούνε)
Forms in parentheses are less common and may be vernacular or poetic; forms after commas are alternatives where both are reasonably common.
The first and third groups are pretty much the same, except for the position of the stress and the second person plural εσείς forms; the second one is a bit different because you see an -a- in some forms.
These come from verbs whose stems end in -a or -e before the endings, where those vowels fused with the ending in many cases, so an original θεωρέω turned into θεωρώ and αγαπάεις turned into αγαπάς, etc. (There used to be verbs in -o which contracted as well, but in Modern Greek those pretty much all got regularised into -ώνω, which inflect after the first pattern. So you have e.g. δηλώνει and not δηλοί.)
This also explains why the εσείς form is different in the first and third groups: a proto-form similar to θεωρέετε (with -ετε ending) contracted the two vowels to a "long" vowel: θεωρείτε.
The conjugation of είμαι is irregular but is similar to passive conjugations, e.g. λύνομαι λύνεσαι λύνεται λυνόμαστε λύνεστε (λυνόσαστε) λύνονται - αγαπιέμαι αγαπιέσαι αγαπιέται αγαπιόμαστε αγαπιέστε (αγαπιόσαστε) αγαπιούνται - θεωρούμαι θεωρείσαι θεωρείται θεωρούμαστε θεωρείστε θεωρούνται.
Nice summary, mizinamo. lfd's right though, it would probably make more sense to have this as κολυμπει, given that is more common and is more in line with how the other verbs are conjugated.
κολυμπεί is not an option, though, as the verb stem has an alpha at the end.
That's a bit like saying "it should be he flys as just adding an -s is more common and is more in line with how other verbs are conjugated"... but verbs in stressed -y turn it into -ie- before adding -s.
κολυμπάει should be accepted in an English-to-Greek sentence, though. (If not, report it.)
I'm not quite sure of the usage of the two variants. I think that αγαπώ, κολυμπά etc. are a bit more formal compared to αγαπάω, κολυμπάει etc., but both are used.
My Greek textbooks (Επικοινωνήστε ελληνικά) mention κολυμπά or αγαπά in the grammar tables at the end, but throughout the book they aren't really used, it seems to me that the variant forms for εγώ and αυτοί are more common.
Ok.. How can I determine this? What indicates this (some specific fish, not fish in general) in this proposal?
If the sentence's meaning was general, the sentence in Greek would be in plural, because that's how it's commonly used for countable nouns (τα ψάρια κολυμπούν, οι γάτες νιαουρίζουν, τα πουλιά πετάνε). Now that there is an article in singular, it is safe to assume that the meaning of the sentence is not general.
I don't think the audio is correct for the word "κολυμπά". I checked on forvo and acapela and there is no "m" before "b".
The pronunciations [mb] ~ [b] are in free variation, as far as I know -- you may hear one pronunciation from one person and the other pronunciation from another person without either of them being "wrong".
We were told by a professor of linguistics with a specialty in Greek dialects, a well educated person should pronounce mb.
Well, sometimes, it depends on the word as well. Personally, I don't think I've ever heard a person pronouncing μπ in μπαμπάς as mb. It's just a matter of how words sound best. ^.^