Is this spawning behaviour?

[Sgooosh]

Outdoors you want as much water as possible so it doesn't warm up as quickly.

If you have a below ground pond it will remain cooler than an above ground pond because the soil insulates the water from the heat.

Aquariums can be insulated but once they are warm, it takes longer for them to cool.

Keeping them in the shade can help reduce the temperature but if the air temp is high, the water will eventually warm up.

can i give it a cover? will water lettuce, duckweed, and red root floater help insulate?

 

[Colin_T]

Floating plants will help reduce the speed that the water heats up if the tank is in the sun. The plants take the heat instead of it going straight into the water. However, if the tank is in the shade, floating plants won't make any difference.

Coverglass will help trap heat and if sunlight is shining on the coverglass, it will increase the heat, like a magnifying glass does. If you want a cover to stop the fish getting out, make a wood or plastic frame and put some shade cloth or plastic flyscreen on it to stop the fish getting out.