Hypothesis testing between pooled samples


I'm doing an assignment where we are given three experimental groups where in each group, five biological samples have been pooled to one sample. Therefore i have three groups with one value in each group (the value derived from five pooled samples per group, being sort of a mean).

Is there any test for hypothesis testing here? So far i know that ANOVA and t-test won't work since t-test needs at least two values per group and ANOVA needs a standard deviation. Visual inspection indicates there is a difference. I need to formulate something like "+/+ group was lower by visual inspection/text X/could not be hypothesis tested". How would you do it?

Graph of the values:


Thank you in advance for your discussion.