A man fighting for the return of his two children was concerned about spending time at a specialist unit where his parenting skills could be assessed because no-one was available to care for his son's pet fish, a family court judge heard.
Judge Eleanor Owens said the man felt "very strongly" about the fish and had "got quite emotional" when they were mentioned.
She said he had asked a social worker "whether he could bring the fish with him".
The judge said he seemed to have a "slightly odd order of his priorities".
She concluded that the children, a boy approaching three and a girl aged nearly 18 months, should be brought up by relatives.
Both youngsters had been placed into temporary foster care after the little girl was hurt and concerns were raised about the care they were receiving at home, said the judge.
The couple had now separated, she added.
Judge Owens said the mother, who had behavioural difficulties, had ruled herself out as a carer.
But she said the man wanted the youngsters to be returned to his care.
The judge - who analysed the case at hearings in Oxford and Reading, Berkshire - said social workers had offered the man the option of a "parent and child" placement or a "residential" assessment so that his parenting abilities could be gauged.
"(He) told me that he did not refuse to do this," she said in a written ruling.
"However, it does seem clear that he raised a concern with the social worker about whether he could bring his fish with him.
"Clearly he feels very strongly about the fish as he told me they were (his son's) fish and he got quite emotional when they were mentioned.
"However it does seem a slightly odd order of his priorities that his first concern was about whether or not he could take the fish."
She said the fact the man "did not apparently have anyone else available to look after the fish" also raised concerns about the effectiveness of his "support network".
Judge Owens concluded the man had "some issues around his basic parenting ability" and decided that it would not be safe to allow him to bring up the children.
She ruled that the youngsters should be fostered by relatives - and said their parents would be able to stay in contact with them.
None of the people involved was identified in the ruling.