Answer:
I would put periods between the sentences and connect certain chunks of the sentences adding transition words like "additionally", "next", "lastly", etc.
Explanation:
Derek wanted a ferocious pit bull terrier to scare off burglars. As a result, his apartment complex did not allow dogs and had to settle for additional door locks to keep his place secure. Additionally, Derek kept his pet goldfish, Mr. Jaws to definitely keep his surroundings safe :)
Not sure if the gold fish is necessary and I don't have a lot of context but hope this helped i guess.