Make the verb agree with its subject even when the subject follows the verb.
Verbs ordinarily follow subjects. When this normal order is inverted (reversed), it is easy to become confused. Sentences beginning with there is or there are (or there was or there were) are inverted; the subject follows the verb. The word there is an expletive or placeholder, but it is not the subject.
Occasionally you may decide to invert a sentence for variety or effect. When you do so, check to make sure that your subject and verb agree.
The subject, aquarium and terrarium, is plural, so the verb must be are. If the correct sentence seems awkward, begin with the subject:
Subject-verb agreement at a glance
When to use the -s (or -es) form of a present-tense verb
Exercises:
Subject-verb agreement 1
Subject-verb agreement 2
Subject-verb agreement 3
Subject-verb agreement 4