Learn English – countable form for “literature”

Your search for a rule is admirable, but alas! doomed to failure.

• The plural of fish is fish. Unless you're differentiating between species:

The smaller fishes are more affected by ocean warming than the larger.

Or if you are a mafioso, in which case you say

Vinnie sleeps with the fishes.

Of if you're a theologian discussing the miracle of

the loaves and fishes.

Different species form plurals in unpredictable ways. Both tuna and salmon are their own plurals. Species that end in -ing, like the ling form their plurals by adding a final s, except for grayling and herring. You just have to look it up here. However, if the fish name is the name of a special at your restaurant, you might hear a waitress call out

I need two salmons and three tunas!

She means two orders of the salmon dish and three of the tuna dish.

No matter how many you have in a bowl, you only have fish, never fishes.

• Cakes is the plural of cake. It never means pieces of cake:

  Some cakes have frosting; others have icing.

• The plural of fruit is fruits, but only when you're talking about different varieties:

  Some fruits -- bananas, apples, kiwis -- are good for you. The rest are not. You always eat some fruit.

• Drinks are the typical nonountable nouns, except when you're talking about varieties or individual servings:

Whiskeys are either blended or single-malt.
Give me two whiskeys, two scotches, two beers.

Waters has an additional plural as the naturally occurring water in a location, so during your vacation, you

take the waters at the spa at the hot springs

• Cheese follows the variety rule. If you have three cheeses on your cheese plate, then you have three different types of cheese, even when you have six pieces of cheese total. Same with milk:

I make three different nut milks in my blender -- walnut, hazelnut, and almond.

The plural of beef is beeves, but it's only used to describe individual animals, meat-on-the-hoof, so to speak.

"What is the color of those two dogs?"

Both dogs have the same color.

"What color are those two dogs?"

Both can have a different color, but most likely one color each.

"What colors are those two dogs?"

Both dogs may have the same colors or different colors, but they have several colors each, or at least one of them does.

"What are the colors of those two dogs?"

Both dogs can have the same multiple colors or each be of (a) different color(s).

"Leaves are different shades of brown and red in the fall."

"The reds and browns of the woods in the fall."

As for the names of the colors themselves, they can be countable and uncountable. To differentiate them, you can use "shades" for instance.