That's great news.
As Waldo said, you can have dim lights on in the tank. Back in the eighties or so, I set my tank up with a set of lights from my retired railway-set. Small, low power, lights with a transformer - preferrably with adjustable voltage so you can adjust the light up/down. I think mine were 0.5w/12v ones.
LED's are also available, and not very expensive. Again, you need a transformer and a resistor per LED - you can either use RED or WHITE ones. You need a resistor before the LED so that the current going through the LED is limited to some extent - how much depends on the individual LED.
This page contains some White LED's.
Datasheet.
Per Ohm's
law you get 5v/250 ohm -> 20mA. So you need a resistor that is at least 250 ohm in series with the diode. An variable resistor along the lines would help control the illumination level, so you can dim the lights - but most variable resistors start at a resistance lower than 250 ohm, so you need a fixed resistor to determine the minimum resistance.
The long leg of the diode goes to the positive side of the power source, the short leg is negative.
--
Mats