The tank should have a hide space big enough for one fish, or a few of them, but at least 1 cave big enough for two fish to fit in.
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	2:det	_
2	tank	tank	NOUN	NN	Number=Sing	4	nsubj	4:nsubj	_
3	should	should	AUX	MD	VerbForm=Fin	4	aux	4:aux	_
4	have	have	VERB	VB	VerbForm=Inf	0	root	0:root	_
5	a	a	DET	DT	Definite=Ind|PronType=Art	7	det	7:det	_
6	hide	hide	NOUN	NN	Number=Sing	7	compound	7:compound	_
7	space	space	NOUN	NN	Number=Sing	4	obj	4:obj	_
8	big	big	ADJ	JJ	Degree=Pos	7	amod	7:amod	_
9	enough	enough	ADV	RB	_	8	advmod	8:advmod	_
10	for	for	ADP	IN	_	12	case	12:case	_
11	one	one	NUM	CD	NumForm=Word|NumType=Card	12	nummod	12:nummod	_
12	fish	fish	NOUN	NN	Number=Sing	9	obl	9:obl:for	SpaceAfter=No
13	,	,	PUNCT	,	_	16	punct	16:punct	_
14	or	or	CCONJ	CC	_	16	cc	16:cc	_
15	a	a	DET	DT	Definite=Ind|PronType=Art	16	det	16:det	_
16	few	few	ADJ	JJ	Degree=Pos	12	conj	9:obl:for|12:conj:or	_
17	of	of	ADP	IN	_	18	case	18:case	_
18	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	16	nmod	16:nmod:of	SpaceAfter=No
19	,	,	PUNCT	,	_	24	punct	24:punct	_
20	but	but	CCONJ	CC	_	24	cc	24:cc	_
21	at	at	ADP	IN	_	22	case	22:case	_
22	least	least	ADJ	JJS	Degree=Sup	23	nmod	23:nmod:at	_
23	1	1	NUM	CD	NumForm=Digit|NumType=Card	24	nummod	24:nummod	_
24	cave	cave	NOUN	NN	Number=Sing	7	conj	4:obj|7:conj:but	_
25	big	big	ADJ	JJ	Degree=Pos	24	amod	24:amod	_
26	enough	enough	ADV	RB	_	25	advmod	25:advmod	_
27	for	for	SCONJ	IN	_	31	mark	31:mark	_
28	two	two	NUM	CD	NumForm=Word|NumType=Card	29	nummod	29:nummod	_
29	fish	fish	NOUN	NNS	Number=Plur	31	nsubj	31:nsubj	_
30	to	to	PART	TO	_	31	mark	31:mark	_
31	fit	fit	VERB	VB	VerbForm=Inf	26	advcl	26:advcl:to	_
32	in	in	ADP	IN	_	31	obl	31:obl	SpaceAfter=No
33	.	.	PUNCT	.	_	4	punct	4:punct	_
