飼育のコツと説明

つぶらな瞳と一生懸命に砂を食む愛らしい姿を見れば。

あなたも一瞬でこの子の虜になってしまうはずです。

Wait, "読点（、）ではなく、句点（。）の直後に必ず
を入れて改行すること。"
This instruction is very specific.
If I write "性格はとっても温和で臆病なので。
", it's a bit unnatural in Japanese to end a sentence with "なので。" but it follows the rule of replacing "、" with "。".
However, usually, "読点（、）ではなく" means "Don't use commas".
And "句点（。）の直後に必ず
を入れて改行すること" means "Every time you use a period, you must break the line".
It doesn't explicitly say "Replace every comma with a period". It says "Instead of commas [implied: use something else or nothing], [and] after periods, break the line."