Fish living in a glass aquarium without a background or substrate stress out and show poor colouration. You have gravel and that definitely helps but the fish would be happier with something on the back of the tank.
Most fish and certainly all freshwater fish naturally occur in environments that have a bottom, sides (usually earth banks or tree roots) and the surface. When you have them in a glass tank they can see through the glass but can't swim through it. This can make them uncomfortable and nervous so adding a picture/ backing to the tank can make a huge difference to their health (reduces stress levels).
You can buy plastic pictures from petshops, they have them on rolls and sell them by the foot. Or you can use coloured card, newspaper, plastic bin liner, or anything that makes the back of the tank appear like a solid object. You just sticky tape the paper or plastic backing to the outside of the tank and it's done. Dark coloured backings show up fish the best and black, dark blue and dark green are the most common but it comes down to what you like. Just try to get a backing for the tank.
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Floating plants help most fish by making them feel more secure. In the wild fish get attacked by birds flying above the water. Floating plants provide somewhere to hide and reduce the chance of birds seeing and attacking the fish. Even tho your fish are inside in an aquarium, they still think the same way, (birds above will eat us, so hide under plants).
Water Sprite (Ceratopteris thalictroides/ cornuta) is a good floating plant and it can also be grown in the gravel. It grows fast and if you get 1 or 2 plants they will quickly spread across the surface and you can start planting them in the gravel, or sell them back to the pet shop.
Rainbowfish will lay their eggs in the roots of floating plants and Water Sprite has a really good root system for this. Pseudomugil furcatus and connieae only produce 1 or 2 eggs per day but the eggs are big and can be seen on the plants roots. The plant or plant roots with eggs can be cut off the plant and put into a hatching container and the fry can be grown up and added back to the colony when old enough.
The following link has info about breeding fish and culturing live foods for baby fish.
http://www.fishforums.net/threads/back-to-basics-when-breeding-fish.448304/#post-3790221
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As far as I'm concerned, airstones bubbling away in aquariums are essential to maximise the oxygen levels in the water. Without an airstone bubbling away, fish can suffer or even suffocate from low oxygen levels caused by a build up of carbon dioxide (CO2) that comes from the fish, as well as bacteria living in the filter, substrate and tank, and the plants when there is no light for them to photosynthesise.
The only tank that shouldn't have an airstone bubbling away is a planted tank that gets supplemental CO2 when the tank lights are on. In this type of tank the airstone drives out the excess CO2 and the plants don't do as well. But even these tanks can have problems at night when the lights go out so the CO2 needs to be turned off when the lights go out or an airstone needs to come on after lights out so the fish don't suffocate. In every other aquarium that is not getting supplemental CO2, an airstone should be used continuously.
dead this morning. If anyone has insight please let me know!
