English equivalent to "a small fruit in an elephant's mouth"

In the Indian language of Malayalam, there's a saying "Aana vayil ambazhanga", which literally translates to:

A small fruit in an elephant's mouth.

It means:

Having too small an amount for a very large need.

What's an equivalent idiom in English?

"Bring a knife to a gunfight", can mean entering a conflict without preparation. "Too little, too late" can mean something is not in time to be effective. These don't fit here, because I want it to only mean "too small an amount for a very large need" and nothing more.

Try drop in the ocean, defined by Cambridge dictionary as

A very small amount compared to the amount needed.

"A drop in the bucket / ocean" is the idiom for your context. But, there are some short phrases that could be used.

"Practically (or virtually) nothing" means it is too small to satisfy any needs. For example:

A small fruit in an elephant's mouth. That's practically nothing.

You could also consider using "a mere smidgen".

This page seems to be trending toward noun phrases (although "bring a knife to a gunfight" is, obviously, a verb phrase).  Another verb phrase that may fit your need is scratch the surface:

To deal with only a very small part of a subject or a problem:
The amount of aid that has been offered is hardly going to scratch the surface of the problem.
                        — Cambridge English Dictionary

Investigate or treat something superficially, as in
This feed-the-hungry program only scratches the surface of the problem.
                        — Dictionary.com

I think you might consider something like "pissing on a forest fire" or "spitting on a house fire" but these are very regional and informal.