I've just introduced some new guppies to my tank (18 in total). However since adding them 2 days ago, they are staying at the top of the tank (surface area) and 2 have already sadly died.
I have tested the water quality for nitrates, nitrites, ammonia, pH with my test kit and the water is showing healthy. Inside the tank I also have a handful of tiger barbs, neon tetra's and a ruby shark. These fish were in the tank before adding the guppies and are having no problems at all. Happily swimming about doing their thing!
I initially thought maybe it was an oxygen problem despite having a healthy selection of plants, so I have increased the power from the air stone and also completed a 50% water change. Nothing has changed.
I haven't had guppies for about 2 years, am I forgetting something that is specific to them?
There are a few possibilities: * the filter bacteria are struggling to catch up with processing the additional fishes' waste - for the next 6-8 weeks, do daily/twice-daily testing of ammonia, nitrates and nitrites with a liquid-based test kit, and if there is any presence of ammonia or nitrite, do additional/larger water changes as per https://www.fishkeeping.co.uk/articles ... ammonia-nitrite-spike.htm [...or, the more likely explanations, if your water quality is still/currently showing 0 ammonia and 0 nitrite...] * the tiger barbs are harassing the guppies (when you're not looking) - often, tiger barbs are best kept in a species-only tank, and the guppies' fancy tails may be too tempting for them to resist; * what is your water hardness levels in CaCO3 or German degrees hardness? (Water/utility website ought to give the specific results or GH/KH tests.) If below the required range (143-536ppm/CaCO3), it may be that the guppies can't tolerate this.