How long has this tank been set up for? The presence of nitrite indicates that either;
a. The tank is stilll going through the cycling process that started when the start was first set up and the fish were added, or
b. Something has caused the tank to mini-cycle (like washing the filter sponges out in plain undechlorinated tap water or adding too many new fish at once to the tank etc), or
c. The filtration is simply not adequate for the tank and cannot handle the bioload of the fish
For more information on what is cycling and how it works, see this article;
http
/www.fishforums.net/index.php?showtopic=10099
We need some more info on your situation to figure out why there are nitrites in the tank, as it is important to sort this problem out as this is most likely what is causing the guppy to act and look off-colour
. So,
a. How long has the tank been set up for and how did you go about cycling it exactly (cycled with fish, fishless cycled, cloned the filter bacteria etc)?
b. How often do you do water changes and how much water do you take out on average?
c. What sort of filtration do you have in the tank and how do you go about cleaning it?
d. How often do you clean the substrate in the tank and what sort of substrate do you have (like gravel or sand etc)?
e. How long have you had the current fish in the tank and when did you introduce each type of fish to the tank etc?
f. What sorts of food/s do you feed the fish and how much/often on average
?
Guppies hate current and loaches love it. If the loach is happy but the guppy is miserable I'd say the current is the problem. .
Not true, guppies are fine in the current, its the nitrite thats causing the problem.
That is sort of true. The nitrites are what is most likely causing the guppys odd behaviour in this case, however delta tailed male guppys which have particularly large tails may have difficulty in swimming about in tanks which have strong filtration and powerful water flow, its the same sort of problem that male betta's have in such tanks.
However most types of guppys sold in petshops don't have a problem with this sort of thing depending on their tail size
.
