Did I ruin my LEDs?

I hooked up a 12v 5A power supply to three XM-L LEDs wired in series, not realizing that they needed something to regulate the current. They were on good heat sinks, and I connected them through a multimeter to see what amperage they would draw. Well, the meter indicated they pulled over 6A and they started to smoke a little before I could disconnect them. When I hooked them up individually to a 18650 (after the previous "test") they seemed to light and work fine, but I wonder if I've damaged them. Do you think I should replace them? (They're going in an aquarium lighting set up.)

If they light fine, and aren't angry blue, they should be fine. Expect them to potentially have a shorter life, though.

They are not blue. (I've seen that before.) I'll give them a try and see how long they last. I will say this, they were REALLY bright @ 6A!

from my experience the light output / efficiency of the LED will decrease.

LEDs are not filament bulbs. Bulbs may give off light from 6 volts to 16 volts. An LED can increase its current tenfold if you increase the voltage by one-tenth.

A series resistor will limit the current change if you use constant-voltage source.

There seems to be only one person on CPF who believes it's a good idea to drive LEDs by constant-voltage control rather than constant-current control.