Black Skirt Tetras

[SkydiveSonic]

My girlfriend has a 20 gallon (US) tank with 6 fish in total (3 lemon tetras and 3 black skirts). The tank has UGF filtering only. She was wondering why her black skirts are more of a silver colour, especially compared to the skirts in my tank. Her water quality is ok (can't give stats on the water as it's not my tank), they eat on a regular basis, have enough hiding places etc. I know stress can be a factor - are there any others that could cause a lack of colour in the tetras?

 

[CroNiC]

My girlfriend has a 20 gallon (US) tank with 6 fish in total (3 lemon tetras and 3 black skirts). The tank has UGF filtering only. She was wondering why her black skirts are more of a silver colour, especially compared to the skirts in my tank. Her water quality is ok (can't give stats on the water as it's not my tank), they eat on a regular basis, have enough hiding places etc. I know stress can be a factor - are there any others that could cause a lack of colour in the tetras?

When did she get them?

 

[SkydiveSonic]

One a few years ago, the other two about a week or so ago.

edit: The 2 latest additions were fully grown when bought - not "babies"

 

[Lateral Line]

The colour in "black Skirts" or "Black Widows" as many peple will know them fades with age. Stress is also a factor, as is the quality of the stock, and the conditions in the tank. Modern line bred farmed fish are frequently poorly coloured compared to fine specimens. The background and lighting can also affect the colour or the perception of the colour.

One or a combination of these factors could be what you are seeing.

Shoaling fisj like these and the Lemon Tets are alweays happier in large groups. Ideally, if space allows, you should aim to keep 6 or more of each species.