Defining Terms: What are Rainbowfish?
Rainbowfish are a species of fish largely indigenous to Australia and New Guinea (see map below), however a few types can also be found on the island of Madagasgar, just off the African continent. There are several broad genus classifications within the Rainbowfish family however the more popular groups are Melanotaenia, Glossolepis and Chilatherina. Rainbowfish get their name from the multiple iridescent scales that help them show exceptional colour. Even just a quick look at the Melanotaenia splendida splendida 'Deep Water Creek' in the top picture will show you that there a multiple hues of reds, oranges and yellows that blend together and help this fish to show off some exception colours. The 'Rainbow' name is well deserved!
Rainbowfish are a species of fish largely indigenous to Australia and New Guinea (see map below), however a few types can also be found on the island of Madagasgar, just off the African continent. There are several broad genus classifications within the Rainbowfish family however the more popular groups are Melanotaenia, Glossolepis and Chilatherina. Rainbowfish get their name from the multiple iridescent scales that help them show exceptional colour. Even just a quick look at the Melanotaenia splendida splendida 'Deep Water Creek' in the top picture will show you that there a multiple hues of reds, oranges and yellows that blend together and help this fish to show off some exception colours. The 'Rainbow' name is well deserved!
Natural Habitats
Rainbowfish are found in major and minor river catchments, tributaries, lakes, swamps and billabongs throughout Australia and New Guinea. Australia and New Guinea are characterised by a monsoonal climate and so Rainbowfish are forced to adjust to a broad spectrum of water temperatures and pH throughout the year. High levels of evaporation in the dry season can reduce water flows, oxygen levels and increase water temperatures and acidity / alkalinity (depending on the bedrock). Likewise, the coming of the rains can also spell an increase in water flows and a rapid drop in temperatures. Thus, even nature subjects these fish to a degree of turbulence that some of our aquarium fishes will never experience!
If you want an in depth read into rainbowfish habitats, then I suggest you have a look at Adrian Tappins Book "Rainbow Fishes Their Care & Keeping in Captivity." It's free and available in pdf download for anyone who wants to study a little bit more.
pH
Whilst rainbows are typically perceived to be a 'hard water' type species, it has been my experience that this is not the case. Whilst ideal water parameters will vary to some degree dependent on the species, most Rainbowfish will be happiest in water slightly north of neutral. I keep my tank at a pH of around 7.3 and a temperature of about 24C. It's best to bear in mind though that this is a generalism, and any fish keeper should do their research and find out the ideal conditions to keep their specific fish species in. Different species of Rainbowfish may have slightly different preferences, e.g. Melanotaenia praecox prefers a slightly acidic pH whilst Melanotaenia boesemani prefers a slightly alkaline pH.
Flow
In terms of 'water flow, different species will have different preferences, some may like faster moving water than others e.g. Melanotaenia trifasciata would appear to like faster moving water in the wild, whilst some species of Melanotaenia maccullochi may become quite shy, stressed or reclusive in fast moving water in the home aquarium. My experience tells me that Rainbowfish like areas of rest where there is little to no flow, that are close by to areas of moderate flow. Highly oxygenated water is a must for these fish and it will help reduce stress and improve vitality. It seems to me that oxygenation is a characteristic of areas of flow and water action / turbulence of some degree.
Plants
Plants are a key characteristic of the ecosystem of any water body, and any Rainbowfish keeper who challenges themselves to actually maintain a live, planted tank will reap the benefits in terms of water quality, a more natural look and happier fishes! In the wild, plants act as the foundation of the food web, filters for taking metals or impurities out of the water and a home or sanctuary for fish and their prey. They also offer similar benefits in the home aquarium by helping to absorb nitrates and encouraging the growth and development of microfauna. Furthermore, I have not come across a Rainbowfish book or breeder that doesn't insist on the benefits of keeping Rainbowfish in a planted tank. Personally, I keep a number of low light, low maintenance plants such as Anubias, various Vallis varieties,Crypts, Java Fern, Java Moss and so on. I particularly recommend fine leaf plants such as the Java Moss, as it is easy to keep, it can be tied to bog wood to create various artistic effects. Importantly, it can often be a focal point for mating behavior, as it acts as a spawning mop that the males guard as they attempt to encourage females to come and lay their eggs.
That being said, there does appear to be a distinct lack of aquatic plants in some rainbowfish habitats. In such circumstnances, overhanging terrestrial plants make up an essential part of the habitat.
Rainbowfish are found in major and minor river catchments, tributaries, lakes, swamps and billabongs throughout Australia and New Guinea. Australia and New Guinea are characterised by a monsoonal climate and so Rainbowfish are forced to adjust to a broad spectrum of water temperatures and pH throughout the year. High levels of evaporation in the dry season can reduce water flows, oxygen levels and increase water temperatures and acidity / alkalinity (depending on the bedrock). Likewise, the coming of the rains can also spell an increase in water flows and a rapid drop in temperatures. Thus, even nature subjects these fish to a degree of turbulence that some of our aquarium fishes will never experience!
If you want an in depth read into rainbowfish habitats, then I suggest you have a look at Adrian Tappins Book "Rainbow Fishes Their Care & Keeping in Captivity." It's free and available in pdf download for anyone who wants to study a little bit more.
pH
Whilst rainbows are typically perceived to be a 'hard water' type species, it has been my experience that this is not the case. Whilst ideal water parameters will vary to some degree dependent on the species, most Rainbowfish will be happiest in water slightly north of neutral. I keep my tank at a pH of around 7.3 and a temperature of about 24C. It's best to bear in mind though that this is a generalism, and any fish keeper should do their research and find out the ideal conditions to keep their specific fish species in. Different species of Rainbowfish may have slightly different preferences, e.g. Melanotaenia praecox prefers a slightly acidic pH whilst Melanotaenia boesemani prefers a slightly alkaline pH.
Flow
In terms of 'water flow, different species will have different preferences, some may like faster moving water than others e.g. Melanotaenia trifasciata would appear to like faster moving water in the wild, whilst some species of Melanotaenia maccullochi may become quite shy, stressed or reclusive in fast moving water in the home aquarium. My experience tells me that Rainbowfish like areas of rest where there is little to no flow, that are close by to areas of moderate flow. Highly oxygenated water is a must for these fish and it will help reduce stress and improve vitality. It seems to me that oxygenation is a characteristic of areas of flow and water action / turbulence of some degree.
Plants
Plants are a key characteristic of the ecosystem of any water body, and any Rainbowfish keeper who challenges themselves to actually maintain a live, planted tank will reap the benefits in terms of water quality, a more natural look and happier fishes! In the wild, plants act as the foundation of the food web, filters for taking metals or impurities out of the water and a home or sanctuary for fish and their prey. They also offer similar benefits in the home aquarium by helping to absorb nitrates and encouraging the growth and development of microfauna. Furthermore, I have not come across a Rainbowfish book or breeder that doesn't insist on the benefits of keeping Rainbowfish in a planted tank. Personally, I keep a number of low light, low maintenance plants such as Anubias, various Vallis varieties,Crypts, Java Fern, Java Moss and so on. I particularly recommend fine leaf plants such as the Java Moss, as it is easy to keep, it can be tied to bog wood to create various artistic effects. Importantly, it can often be a focal point for mating behavior, as it acts as a spawning mop that the males guard as they attempt to encourage females to come and lay their eggs.
That being said, there does appear to be a distinct lack of aquatic plants in some rainbowfish habitats. In such circumstnances, overhanging terrestrial plants make up an essential part of the habitat.