"There are little red fish."
Translation:Il y a de petits poissons rouges.
Not an idiom. Whenever you have the indefinite article "des" in front of an adjective + noun, "des" becomes "de".
des enfants → de petits enfants
des yeux → de grands yeux
des hommes → de jeunes hommes
So two adjectives describing the noun. Why does one go before and one after the noun?
Some adjectives go before the noun and others go after.
Examples of those that go before (BANGS):
Age (jeune, vieux)
Number (un, deux)
Goodness (bon, mauvais)
Size (petit, grand)
The adjectives that do not fit in these categories go after. There are a few exceptions, but this is a good general rule. (colors, shapes, origin, material, type, etc.)
"Il y a" is a fixed expression. It may be translated as either "there is" or "there are".
I thought that if there were 2 adjectives that we did not pluralize them. Is this only if they both appear after the noun?
The rule of "two adjectives" only applies if one is modifying a color: bleu foncé, gris pâle, vert clair. This is when you have a compound (2 part) color adjective. Otherwise, adjectives DO follow the gender and number of the noun they modify.
The English sentence is plural, there are (meaning more than one) little red fish. If it were singular, it would be written, there is a little red fish.
In English, the plural of fish is... fish in almost all cases*. Certain nouns are the same in the singular and plural forms: a moose, moose / a deer, deer / a grapefruit, grapefruit.
- Fish can be correctly written as "fishes" if the meaning is multiple "species" of fish. This is usually in a scientific context.