nitrites are high considering the bioload in animal form, what you been feeding & is carcus extraction been 100% accounted for? How old is the tank? Whats your lighting & cycle info?That Algae is nasty stuff cause it'll spread like a B$%tch, but unless it over takes your static animals isn't not much to worry about really as its actually consuming your nutrients to reproduce, try to improve water quality & increase your changeout amounts coupled with manual removal & an active mental decrease in your nutrient inputs for awhile should reduce it over time. Persistance is the key, but yeah, besides that spike it doesn't paint the full story yet as to why things perished. answer the above, others will chime in soon & it'll get both you & us to a beter understanding of whats happened or could of happen, & hence how to correct it!
