Its natural for some babies to be eaten by adults and if all of them survived your tank would be very overcrowded.
1-2	Its	_	_	_	_	_	_	_	_
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	3	expl	3:expl	_
2	s	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	cop	3:cop	_
3	natural	natural	ADJ	JJ	Degree=Pos	0	root	0:root	_
4	for	for	SCONJ	IN	_	9	mark	9:mark	_
5	some	some	DET	DT	_	6	det	6:det	_
6	babies	baby	NOUN	NNS	Number=Plur	9	nsubj:pass	9:nsubj:pass	_
7	to	to	PART	TO	_	9	mark	9:mark	_
8	be	be	AUX	VB	VerbForm=Inf	9	aux:pass	9:aux:pass	_
9	eaten	eat	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	3	csubj	3:csubj	_
10	by	by	ADP	IN	_	11	case	11:case	_
11	adults	adult	NOUN	NNS	Number=Plur	9	obl	9:obl:by	_
12	and	and	CCONJ	CC	_	23	cc	23:cc	_
13	if	if	SCONJ	IN	_	17	mark	17:mark	_
14	all	all	DET	DT	_	17	nsubj	17:nsubj	_
15	of	of	ADP	IN	_	16	case	16:case	_
16	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	14	nmod	14:nmod:of	_
17	survived	survive	VERB	VBD	Mood=Ind|Number=Plur|Person=3|Tense=Past|VerbForm=Fin	23	advcl	23:advcl:if	_
18	your	your	PRON	PRP$	Case=Gen|Person=2|Poss=Yes|PronType=Prs	19	nmod:poss	19:nmod:poss	_
19	tank	tank	NOUN	NN	Number=Sing	23	nsubj	23:nsubj	_
20	would	would	AUX	MD	VerbForm=Fin	23	aux	23:aux	_
21	be	be	AUX	VB	VerbForm=Inf	23	cop	23:cop	_
22	very	very	ADV	RB	_	23	advmod	23:advmod	_
23	overcrowded	overcrowded	ADJ	JJ	Degree=Pos	3	conj	3:conj:and	SpaceAfter=No
24	.	.	PUNCT	.	_	3	punct	3:punct	_
