Fish dying and deflated anemone

Question
Hi David,
I have judt set up a 14" (12 gallon) minicube tank with live rock (some old/dead and some new) with purchased seawater with a dual (white & blue) light on top.  I had the tank cycling for just under a week and then added a bicolour blenny, a Sebae Anemone, a couple of coralmorphs
and a torch.  I only had the blenny for one day in which it seemed really ahppy and today it is dead, the anemone is deflated, the coralmorphs are screwed up and the torch is closed.  I have checked the nitrites and they are less than 0.5ppm.  What could be the issue and how do I fix it??
Many thanks in advance.
Kind regards
Kate
Kate

Answer
Hi Kate Sunn,

Sorry to hear about your losses.

Regarding Your 12 Gallon Aquarium:

You can be successful with a nano reef aquarium, however patience is key, along with keeping your water very pristine.

Cycling your marine aquarium, for the very first time, for just under a week is not long enough. An aquarium of this size, with the added live rock, should have been cycled for a minimum of 4 weeks or longer, while monitoring and keeping an accurate log of the water parameters, along with doing a partial water change, before attempting to add any marine life. Cycling gives the aquarium water a chance to balance out in many ways, including letting the live rock finish curing, and letting your beneficial bacteria grow and colonize.

Regarding your nitrite, they should have tested at 0 ppm. Both Nitrite and Ammonia levels, should always test at zero. Minute levels of Nitrates are acceptable, but should always be kept as low as possible. This is accomplished by doing water changes, and by having adequate filtration.

Since your aquarium is small, special care and attention will be needed, to make sure the water quality is always kept at it's best, especially when keeping anemones. Anemones come from very pristine coral reefs in nature. I recommend for you to add a protein skimmer, if you don't already have one.

Regarding a Sebae Anemone, the minimum required aquarium size for this marine animal is 30 gallons. When selecting marine animals, make sure your aquarium is suitable for them, in terms of size, lighting, filtration, fish compatibility and coral compatibility. A good starting point, is to read up and educate yourself on any species that you are interested in and intend to keep.

I wish you the best of luck in all your saltwater aquarium endeavors.

Regards,
Dave